Fast fall is a very difficult thing to pick out from the vids so far. I'll give them another look an see if there's anything obvious, but not sure we'll be able to confirm it yet.
EDIT - ok the only thing I see for fastfalling occurs shortly after 0:20 in this video (
https://www.youtube.com/watch?v=e-hPRocg8Yw), where the "sparkle" effect that occurs when fastfalling in previous games occurs around Megaman... he's so close to the ground that it's hard to see a change in fall speed, though.
I made a gif of it, but it's a bit hard to see..
http://imgflip.com/i/2iwkx
I also found it interesting that Mario's fall speed seems...inconsistent in the video. It seems like he's fast-falling at times, but no sparkle occurs or anything... his speed just changed. I say we file this one in the "probable" column... I think we all expect it, and have
some evidence, but nothing terribly solid.
Looking for FFing in the video has definitely made me realize that the fall speed is MUCH faster than Brawl's, though.