I’m not sure, but I think they get paid for keeping your attention.
And if they offered a short summary in the notes, or at the beginning, lots of people wouldn’t stick around to see the video.
Yep. Longer vids mean more revenue. I spot check vids now if I’m interested in it. If you skip to minute 7 or 8 of a ten minute video you are usually pretty close. Some vids are excellent and worth the time. Too many are just padding.