Well, my game is a 300Kb download.
And the video is 11Mb.
Personally it's seems stupid to download the video when you can get the game, however if the videos are compiled together, then I suppose it'd be better for people who don't want to download 23 games and try them all out....
Well, for those of us with high speed connections download sizes below 100 MB don't make much of a difference (assuming the server is decent). Downloading and playing all the entries is a LOT of work and I still haven't got around to playing more than a handful. A video would be very helpful in getting a good overview and highlighting the interesting games that could be worth downloading, even if it's 20, 30 or 50 MB.
Concerning video speed, someone (either the original author or the one making the compilation) should be able to speed up videos to approximately match the game's original speed. Authors who don't want to bother doing that themselves could supply a note that provides an approximate guess at what percentage the video needs to be sped up (from calculating fps ratios or just plain gut feeling). Then Matt could do the actual time stretching.
If there's a note in the beginning of the video stating that game footage might not be entirely accurate in terms of speed, I don't think people would be put off by a segment that's somewhat slow if the game looks good otherwise.
Of course you should try running the games in as low a resolution as possible to minimize capture overhead.
(I still haven't recorded mine... hope we still have some time

)