Definitely the shorter the better but don't abbreviate words, If you can just go www.site.com/videos/[video name] that would definitely give an improved signal over and above longer URLs of competition.
Or you could possibly get away with www.site.com/blog/videos/[video name] this would carry a little bit less weight but be more descriptive.
Definitely rule of thumb the shorter the URL the better, do not abbreviate, (Google may not know what it means).
