Need more clarification on how YouTube's offline video feature for mobile will work? Well, All Things D has shed a little light on the process via a memo Google sent to its YouTube partners. Turns out, offline video will be enabled by default in the YouTube app when it goes live in November, but wary partners do have the option to opt-out and can make that change right now. On the viewer end, all cached videos, accessible through the YouTube app's "on device" section, will be available for a 48-hour offline window that refreshes whenever the app reconnects to the internet. And, yes, there will be ads, but they'll be of the in-stream variety only. The new functionality doesn't apply to any movies or TV shows that Google offers for rent or sale and it's also still unclear if music videos will be whitelisted. But, hey, at least now you'll have one more way to watch this glorious weirdness when you're out of signal range.