Because those videos give Google the best ad revenue. Who cares what the users watch all long as Google gets rich along the way.
What is the mechanism for that? What do you envision makes them more valuable?
Google gets more money if the video has more ads. Google also pays more in bandwidth and storage if the video is really long or high res. Also, advertisers don’t like drugs, violence or guns, whereas makeup and mobile phones are totally fine, so those videos are a suitable background for ads.
All of these variables go into the calculation that determines the sweet spot for Google, and the search results are ranked accordingly. You may be looking for an hour long video essay on the torture methods seen in the Hellraiser movies, but Google really wants you to spend more time on 5-minute crafts instead. Actually, 30 s shorts would be even better, as long as they keep you preoccupied.
