2-10 minute videos are the worst. The information takes forever to get to and is super shallow, and most of them are going to be an advertisement for the youtuber I'm currently watching. A 30 minute video is fine. An hour long video, I'll watch happily. Hell, I've watched movie-length videos on cool subjects with no problem.
But if I have to sit through 90 seconds of "smash that bell, thanks to my new subscribers whose screen names I'm going to read one at a time" before getting a nugget of content that can't be more than a few seconds to a couple of minutes long, yeah, I have no attention span for that shit.