I've been to Belushi's for cricket, lacrosse and hockey. It's attached to a hostel so it's full of expats and backpackers. I find it comfortable. The beer selection is decent and the food is passable. The one downside is they don't usually turn the sound on. I only tried asking once (at 2am on a Thursday night, when half the people in the bar were me and a bunch of Canadians watching the NHL and the sound system was full of techno music) and the guy claimed not to know how to do it.
I've never watched a game at Salamas, but I did recon there. It feels much more like a "Lokal", not very inviting to outsiders. OTOH, people who have actually gone there for games say the proprietor is friendly and accomodating once you get inside.
I also read that the Old Emerald Isle near Kottbusser Tor shows american football. Any truth to that rumor?
We watched the NFL conference championships and Super Bowl there on Sky. I don't have the impression they get NASN though. My experience there is that they'll typically put the sound of the game on in the back room, and it's fun when a few people turn up for it (my last time there was an England-Australia match from the Cricket World Cup). The bar staff aren't too enthusiastic about UK/US sports, though. We actually had a waitress launch into an unsolicited monologue about how boring American Football is during the fourth quarter of the Super Bowl.