The amount of effort that gets "wasted" per unwatched video is probably relatively small. Per the video instructions (http://ycombinator.com/video.html), producing the video really shouldn't take much time at all (my guess is less than five minutes for a group that a) already has well defined goals and b) has a macbook, where there's almost no overhead to record a video).
Additionally, the very act of making the video is likely beneficial to the groups, by forcing them to solidify their ideas enough to be comfortable talking about them and by having them practice giving an elevator pitch about their idea.
It should be even less work than that. We don't care about the pitch in the video. That's already in the application. We just want to see what the founders are like as people.
Trying too hard to pitch in the video is actually a mistake, because it makes the video stilted.
I agree that it take lots of time to make a "professional" looking pitch, but based on the instructions, it looks like pg wants as much spontaneity as is practical.
Try recording yourself doing a one minute pitch. You'll be amazed at how short (to explain what you're doing) and how long (to not blow it) a one minute pitch can be. Now try coordinating 2-3 people doing that.
We're doing a little 1-2 minute video explaining our stuff at the moment and staying rather lo-fi and plan at least 10 hours of work on it.
If that's so, my skills at setting up lighting, choosing angles, and editing, learned on a A-level equivalent Media Studies course, would be more useful than my entire Software Development degree!
