When you watch a film (and record it maybe) and the very second the credits roll, a cheesy announcer comes on and says: "Coming up now it's blah blah blah" and the credits resize to small print and some silly advert for another programme comes on. It can really ruin the moment especially if it's a very emotional film. I love reading the credits, actors, locations and seeing what the songs are if the music was really good.
Another bad one is when adverts come up in the wrong place in films on telly and some of the best jokes or or subtle moments are ruined completely!