You can see the clip -- which is attached to the end of a trailer for Arrow's finale -- here, but what's most interesting is that the blur at the end of the clip can, in fact, be identified as humanoid.
Going frame by frame, ComicBook.com has tracked down your first look at The Flash in motion. Check it out below.
As many had predicted, star Grant Gustin's costume looks much better in motion, with CGI and all the rest applied to it -- although it's still not totally clear where the "lightning" effect is coming from seeing as the gold details on this costume are slim to non-existent. That's a minor quibble, though, since ultimately it looks cool and it's consistent with what people will expect from the comics.