What should I do if I catch my brother masturbating?

Ok Im 14 hes 12, and this is the first time ive ever caught him doing something like this before. What happened was that I am sitting at my laptop and to my left is my brother sitting on the couch playing xbox. I can only see his head but today I saw a suggestive concept art sketch on the TV and I also saw my brothers head moving up and down rapidly. He was doing this for a good 30 second when i decided to walk past him. I made it look like I was just getting up to go to the bathroom but I saw the xbox controller on his crotch area moving up and down. he stopped right as i passed by and blushed but i didnt do anytihng so he didnt realize that i had caught him. Im wondering if i should talk to him about it or something. It would embarass him but atleast it wud stop him from jacking it right next to me and the awkwardness i feel. thank you for your time