I'm definitely one of those people, but I work in an office where they let us watch shit on our phones as long as the work still gets done. A hell of a lot easier to watch YT videos than to try to sneak an Xbox S into a cubicle farm ¯\_(ツ)_/¯
"Videos about gaming" don't necessarily have to be gameplay footage. Reviews, promotional materials, discussions etc. count. Maybe even stuff like Viva La Dirt League's content which is live action skits about video games.
Tutorials and walkthroughs exist.
Some vintage systems are difficult to get up and running or even find. For a lot of people it's easier to just watch an enthusiast do it on youtube.
Especially on Twitch with streamers it's as much about the player as it is the game.
Especially with esports or speedrunning it's like watching a sporting event. Even if you like playing football too there's something to watching the professionals play at the top echelons.
One can watch gaming videos while doing other things. When I was moving into my apartment in Greensboro I assembled my furniture while watching HCBailly play through the Gameboy Zelda games.
Same. Not only is it little effort, but you get to experience what the intended purpose of the game was without having to listen to some rando try out bad jokes or say lame stuff. Any time I look at a video tutorial I look for videos with no narration and once I figure out how to solve the problem I turn the video off and get back to the game. Watching someone else play a game just seems like a waste of time, personally