Wow...
normally I try to stay out of the "I NEED WAVEDASH IN BRAWL, ZOMG THERE IT IS, PROOOOOF!!!!" threads, but that is actually really great evidence of a waveland right there. The only other thing that could possibly be causing that smoke would be that Wario is now more slidey than Luigi.
Now most people have surmised that based on the videos, Wario will be a pretty weird character, so it could be possible that he slides that far. But still, that's the probably the best evidence I've seen so far.
EDIT: well apparently everyone else thinks this is a slide as well. It probably makes sense though. Why would Sakurai include a hidden advanced technique in a video designed to show the basics of a new game.