Congrats on the great idea. I agree that it has potential applications for educational videos. I tried with the circumcenter video I made when I was a teacher. (Bug alert: my comment on Quip was supposed to include the text "mind=blown" but it turned into "mindblown".)

Hopefully I'll see you at YC this summer! My startup is also having fun with video timestamps, though in a very different way. I think now is the right time for that. Anyway it was fun playing with Quip. Let me know how I can help it catch on! Maybe we can partner up. I'll PM you. It would be funny if 10 years after being math majors together we ended up doing video stuff together. That would be like...mind=blown.