I don't find it all that hard to watch other people play, seeing as most take my advice and understand what I'm saying pretty easily. The opposite is rather annoying though, especially around rowdier and snarkier friends. I'm big into RP, to the point that immersion is one of my most coveted qualities in a game. I often find myself thinking of scenarios and small stories for my actions in a game (Just recently I was going over the thought of my tribe of bird-folk's exploits in Spore in cinematic format). That being so, having someone crack a joke at the unusual nature of a game throws off my immersion and irritates me to no end. Another problem with my immersion is that I pick up my surroundings a lot faster than most. The following scenario usually occurs:
Me (thinking): Alright, there's three enemies with assault rifles in the main field, one behind them with a missile launcher, and a sniper hiding off to the right. Let's sneak over here like so...
Friend: Look, bad guys!
Me (thinking): Yes, I see them. Alright, let's get a grenade in there, and...
Friend: Look out, one of them has a rocket launcher!
Me: Mmhmm. (For christ's sake, I can see. Let's just go over here and gun him down, and run to some cover to take care of the sniper...)
*several seconds pass, in which the sniper has taken a couple of shots at me and it's pretty obvious I'm hiding from him. He might even show up on the screen once or twice in the process*
Friend: Where is he? What's that shooting from? I think he might be over there... Oh, there he is! Up there!
Me: ... (Now I know how Link felt in Ocarina of Time...)