I like some of the other suggestions better than this but if you've already tried communicating about it and other things haven't worked, I wonder if for some cases you could convince him to take a video or a picture. Like, if it's a cool thing he wants you to see instead of interrupting you record it and share it when you're available instead of right now, interrupting you. Again, I think the other proposals are better but I wonder... if you're right about the motivation at least sometimes being just wanting to share something it might be worth attempting.