Monetizing of the online video "industry" directly lead to this kinda of video where a 2 minute talking point is padded out to more than 20 minutes. A passionate person would be trying to get the point across for their viewers not getting the 5th mid-roll ad in.

Watch videos by Mike Harrison (Mike's Electric Stuff) or Ben Krasnow (Applied Science), while they do occasionally run long, the videos are so dense that you can't skip 75% and still know what's going on.