I look at someone like Rainman Ray, who went out on his own and opened his own shop late last year after getting fired from his day job.
From what he's said in his videos, he basically picks and chooses what he works on these days. If I had to guess, his repair income is probably pretty low and instead the shop is more or less just a way for him to always have fresh content for his channel. I only watch him in spurts, but I recall one where he was working on a Jeep rear end and promised to supply some uprated/high end parts on his own dime if the video got XXX views and/or got him a certain number of new subscribers. That makes me think that a few hundred dollars in differential parts were probably minor compared to the income/views from all of those people.
There's serious money in it for people who can get a good following, and unfortunately the quality of information at least for some can come secondary to just generating the clicks and views.
There are algorithms that calculate things like watch time and as I understand it the higher your percentages of watched videos, the better it is for money making. I have been posting videos this summer for an online asynchronous class I'm teaching(it's been a project in planning for a while but not actually executed). I can see all these stats, but of course am not actually making money off them and wouldn't be able to as I don't have anywhere near the views or subscribers. About half my traffic comes from the links I post on Blackboard and the other half comes from pretty much anywhere, so at least some people seeing them. I can see all of these stats, though, like percentage watched and so on.
To that point, though, I suspect that's why some channels run as they do. Project Farm talks like he drinks 3 pots of coffee before every video probably to make them short enough that people will watch through. Taryl Fixes All eats up the first couple of minutes of every movie with a stupid, corny skit because it increases watch time before actually getting to the content.
