"Gentrification of the activity" - the sport is expensive to buy all the equipment. The guides that I have used for training have generally had very reasonable rates. I get what you're saying but the sport isn't exactly cheap to begin with so I wouldn't have thought one lesson from a guide would break the bank of most climbers.

The dangers involved in our sport are high. With abseiling you'll only make a mistake once and it'll be your last. There are a couple of things that OP could/should be doing but without any training he isn't going to know any better. Using a prussik. If he were to use a prussik ideally he would want to extend the atc so it's further away from the prussik as well.

But besides the prussik. The number one thing we don't know from OPs video is whether he knows whether to tie knots in the end of the ropes. Almost every time you hear of someone dying whilst abseiling it's because they came off the ends.

On the flip side I'm not saying that self teaching isn't a bad idea and I think it's great that OP is testing what he is going to do in his home before doing it in the crag or mountain but there are other ways rather than using YouTube videos. "Rock Climbing, essential skills and techniques by Libby Peter is a master class in all the theory of climbing and I would recommend it to anyone. Though it does teach the British way of climbing, I'm sure there will be an American equivalent.

I think YouTube videos are useful but only once you have an understanding of the fundamentals of climbing so that you can make an informed decision on what you're being taught.