How does it work on iOS?

Firstly, does EveryPlay take advantage of non-public areas of Unity? In other words, if I wanted to create something similar to replace EveryPlay, could I?

Second, is there any docs or source code showing how it works (low level)?

I'd like to record the screen to video, just like EveryPlay, on iOS only, but the only advice I can find online are people using AVAssetWriter (iOS native class) and sending in periodic pixel level screen data (which really slows down the app).

I wish I could just use EveryPlay, not a fan of reinventing the wheel, but sadly I really need to be able to post videos *directly* to Instagram and Facebook, not have them be links to everyplay's website... As my daughter is quick to point out, "nobody clicks links, it's 2016". So I'd just like to write native iOS code to record the screen to a video file which users can share like they would any video (my target audience knows how to do this part).