Most Helpful Guy
"Hey I need you to come watch me get my nails done while I plan out a night with my girlfriends" "well how bout I just don't watch you play video games then?"
Or "hey this isn't fun, I hope you aren't leading up to making me watch you jerk off."
Or just "I don't want to make you feel bad but I don't enjoy watching you play games."
I'd say be honest. He probably just wants to share something he enjoys. Unless he's a weirdo and it makes him feel extra manly to make you watch him succeed at doing nothing. I feel like you might equally ask him to listen to you read out loud to yourself even though he doesn't like the book. Mm seems more childish this way.
Most Helpful Girl
If he's your boyfriend you should feel comfortable in telling him what you like and don't like, you can just tell him "I get bored watching you play video games, lets do something else"