No, I didn't see that video but I wouldn't be surprised that people make up all sorts of excuses. Prior to these laws I hated using my phone in the car. Before my smartphone I never talked much on the phone so it wasn't much of an issue anyway, but I think I can recall using it about 5 times in total while driving and that was to say "hold on, I'm pulling over". Never dialed a number. Hated the distraction.
So it pretty much goes without saying that while I have music playing form my phone about 40% of the time I drive, I couldn't care less about what the law says because I never pick it up. While I can't speak for the Snapchat addicts, having a phone sitting loosely in a cup holder playing music is in no way a danger and shouldn't be the subject of enforcement action.
As for the rolling stop lesson, maybe someone should have a chat with this guy:
Oh, and his two consecutive failures to signal his two prior turns...