Why is this song used in so many GoPro videos?

February 23rd, 2012. Electronic violinist Lindsey Stirling uploads the official music video for "Crystallize" to YouTube. Two days later, user "riley lux" uploads a video titled "DH long boarding on a windy day." In it, a group of friends enjoy some downhill riding set to Stirling's haunting violin-based soundtrack. The video itself isn't remarkable. Some self-shot GoPro footage, with a few edits roughly in time with parts of the song. But, there's something about each pass of Stirling's bow that balances the on-screen energy with a tangible calm. Later the same day, user "Jvr0s" chooses the same song for a video called "GPK Fun around town." In it, a group of friends practice parkour. This video is entirely forgettable, but for the song -- it somehow manages to elevate the otherwise unremarkable action cam footage.

My first exposure to the track is also on an action sport video, during a wingsuit video marathon, to be precise. Long after my first encounter, I hear the song again on an F-18 pilot's GoPro video; remembering it, I use Shazam to find out what it's called. I scour my YouTube history and realize: This song has been following me for months through its popularity on YouTube GoPro videos and I've only just noticed.

The question is: Why am I hearing this song in videos more than... well, any other? Is it a free download on some action sports site? Was it used in an advert for GoPro? Maybe it's just confirmation bias? Or, perhaps, Stirling's stumbled on a secret formula. Something in the song's DNA that makes it particularly suitable for soundtracking sweet jumps, aerial rides, hula-hooping, surfing, wingsuit flying or, seemingly any and every form of action-based activity?

As of this writing, searching YouTube for "Crystallize GoPro" returns about 12,000 results. By contrast, searching for "Rihanna Diamonds GoPro" (an arbitrarily chosen popular song), you actually get about 10,000 more results. However, scroll down and you'll soon see that the action videos using Rihanna's song are few, and drop off almost immediately. YouTube fills the space with "Results for similar searches." You can go 10 pages deep after searching "Crystallize GoPro," and still find more action videos soundtracked by the song. When I first noticed this, it seemed like an in-joke I didn't know about. Some videos are perhaps less suited for the piece, sure; it's not a panacea. But most -- the clear majority -- are improved by it.

Time to call in the professionals. I spoke to GoPro Creative Music Supervisor David Kelley about it. His job is figuring out the best music for GoPro's in-house productions. If anyone knows how to soundtrack an action sport video, it's him. I want to know if there are characteristics he looks for in music that can help explain why "Crystallize" might work more than other songs. (And in turn, what music in general works?) It turns out there are: "We do really appreciate a long intro, dramatic builds, spaces in the song where we can play around with the footage," explains Kelley.

If it were as simple as the structure, though, surely there'd be something of a formula by now? A musical template making Kelley's (and our) job easier? Kelley, perhaps predictably, adds that it's also about the unquantifiable: the emotion of the piece, its narrative qualities. "It's really hard to tell a great story without using music," he says, "because music is the shadow that's telling you how to feel, or what the tone of what you're seeing is."

Where GoPro differs from the average uploader, though, is that it has a library of music comprising some 500 indie artists (representing about 20,000 tracks) for it to draw on. Kelley's skill is finding the right one, but even the professionals aren't immune to a bit of a nudge from their gut or serendipity. "I never thought it would happen, but when the right song shows up, you'll know," he says. "It just makes the footage sing out; there's that magical lightning-in-a-bottle thing that happens."

This "leaping out" is what happened with user "SWISSPilot101." Loïc (his real name) used "Crystallize" on this video of him flying a small aircraft. He tells me he isn't actually much of a fan of Stirling's music, but, "I found this song pretty well fitting. It turned out to be very easy to cut some footage to the song with nice transits. The construction of the song is not too complicated, which makes it easier to fit into a video." True to Kelley's advice, essentially it made his footage "sing out" to him and there were easy edit points, cues for him to tell his story.

"Crystallize" is, of course, not the only song that lends itself to our home videos. There are many; it's just Stirling's that has come to my attention. Another example is Overwerk's "Daybreak"; it's on way more GoPro videos. At least double if we're going by the YouTube search metric. It too has the intro, the high impact beat, the builds and the "space." And so it should. Not only was it used on one of the camera maker's official videos (earning it instant favor with GoPro owners); it was written (or at least finished) especially for the company. When GoPro reached out to Overwerk about working together, he offered them "Daybreak" -- an incomplete track that the artist felt was ideal for the company.

So far, we know that a good intro, hook or dramatic instrumentation (with a healthy dose of storytelling) can help your video and music gel. But, is there something else that ties it all together? Something in the brain? Professor Joydeep Bhattacharya lectures on the neuroscience of music and emotion at Goldsmith's University, London. Unsurprisingly, he says it's complicated. "When a musical piece is chosen to go along with a visual scene, what's needed is the congruency of meaning across both dimensions -- musical and visual," he says. "The answer lies, in my view, not just in the music, but the various ways that meanings emerge out of the video." The trouble being, that meaning is a deeply subjective thing.

Bhattacharya explains that how a video is shot and edited -- the dynamics, the angle, surroundings, et cetera -- all contribute to its relationship with music. In Stirling's case, Bhattacharya attributes the song's "sense of toughness" and "dream-like" state as key to providing meaningfulness to those action enthusiasts choosing it. As a non-scientist, I hypothesize that Stirling's soothing "dream-like" violins subconsciously represent the fabled state of flow -- the state of mindful focus -- often talked about by action sports participants.

This leads us to a (admittedly obvious) question. What is the meaning behind "Crystallize"? Who better to answer that than Stirling herself? "When I finished writing 'Crystallize' and was trying to think of what I should name the song, I had recently started attending some meditative/therapeutic sessions with a friend. She taught me about Dr. Masaru Emoto, and his experiments with water." For those unfamiliar with Emoto's experiments, he believed that water given positive reinforcement, and water given negative reinforcement, when frozen, look vastly different under the microscope. Essentially, that water is changed by consciousness. "Considering that we, as human beings, are over 70 percent water, well -- you get the idea," adds Stirling.

It's perhaps Stirling's own feelings about "Crystallize" that likely chime most with the average big-wave rider or skydiver. "I'd like to think that 'Crystallize' is a very positive, empowering song and that when people listen to it, they feel that enabling power in themselves to go out and achieve their goals and dreams." Even Stirling's noticed its popularity with this demographic: "I haven't searched YouTube for 'Crystallize' lately, but have noticed that people like using it as background music for videos, gymnastics, dance routine music, et cetera," she said. "I think that's awesome!"

Of course, you only have to look at the official video for "Crystallize" to see it. The ice, the rocks, the flight-like shots between the stalactites. In many ways, the first 25 seconds are like the wingsuit videos that started me on this journey. "I don't have a problem with fans using my music for basic [not-for-profit] videos and projects," adds Stirling. Which is good, because it's been three years since its debut on YouTube, and the videos using it are still coming.

If the idea of using a track that features on thousands of other videos horrifies you, GoPro's Kelley has some tips for upping your soundtrack-selection game:

• Get a feel for the tone, the color and the texture of the footage; try to get a clear idea of what the story you're telling is.

• Pick a handful of songs, and play with the footage; see what works.

• Sometimes you just need one part of the song. "We always look for intros that really grab you. Maybe a hook, but they're usually pretty beat-driven."

• Look at a song, and see how you can edit to the music or cut to the beat. Look for cues in the song that tell you where to go. A moment of silence? Perhaps a good opportunity to put a "foot brake" in the video.

• "Sometimes, try and choose music that falls outside of what you normally like. Occasionally a video can call for music that isn't my favorite, but when you see them together, it works."

• "I always encourage directors to reach out to independent artists directly and plead their case. Tell them you're making a short film about [whatever]; you'd love to use their song. More often than not, the artist is honored and will grant you permission."

• Failing that, there are many artists on Bandcamp and SoundCloud that actively want you to use their music. Look around. Additionally, production libraries (like extrememusic.com) can be both inexpensive and convenient for sourcing legal-to-use audio.