from Crystal Furman at the College board (via Facebook).
Crystal Schweickert Furman -- We've had students do this before but they need to be very careful that the quality of the video doesn't suffer and that the reader will still be able to see the elements they need too see to grade. A student submitted at 10x speed last year and that made it close to impossible to understand what was happening in the video.
So there you go. Basically, the spirit is that the video needs to clearly show the core functionality. If that means you need a little bit more than 60 seconds of real time, it's okay to speed it up. But don't push it, and don't try to get away with something
I couldn't find any rule expressly disallowing editing so it's inbounds. I think it's particularly useful in the playing-a-game-to-a-certain-score scenario that @anmrobnott mentioned, where you should how it starts and then maybe zoom through game play, and slow down to show how the endgame works.