The brain is a muscle just like any other muscles. It needs to be trained and strengthened and kept in working order, otherwise it starts rusting, and like a couch potato the muscles turn to mush. When was the last time you gave it some fodder to chew on, something to learn or solve?
There have been studies done where it shows how Skills are correlated to Challenges. If you have mastered your Skills, you might be doing things automatically which means that your brain is feeling restless and trying to find something Challenging to do.
If you feel like you need a YouTube video going, pay attention to what is the content that is coming up on the feed. Is it something that you might be interested in learning about? Is it something that will help you acquire more skills in whatever work you are doing? Or if it is something completely different than what you are already doing, are you OK to learn it only because you feel inspired to learn it? It might lead you to other things that might hold your interest more.
Once the brain is active and happy in one area of life, I have found that it filters through into other areas.