Video should be shot in landscape mode. Look at that giant TV in your living room. Head down the movie theater and check out the silver screen. Both are in landscape and now, finally, Twitter's live video-streaming app Periscope will support the correct orientation on iPhone and Android. But, if you're a fan of portrait videos (you monster) you can continue your upright video shooting ways. For viewers, they can watch videos in either landscape or portrait mode regardless of how they are shot. The app will auto rotate the video to compensate how the phone is held.
Twitter recently added wide aspect-ratio video recording mode support to its own apps so bringing it to Periscope isn't that big of a surprise. Also, with the new tvOS for the Apple TV, you can probably expect a Periscope app to end up on streaming video to your HDTV and for that screen, you want the correct orientation.
In addition to landscape videos, the updated app now tells you which of the accounts you follow shared a video that appears in your home feed. Plus on Android when you start a private broadcast, a list of mutual followers (people you follow who also follow you back) is now available. Periscope says, "we think this list is a more natural selection of people who you are likely to broadcast to." The company also says that this feature is coming to iOS soon.