My kids lead very sheltered lives. They watch the majority of their TV shows from recordings on our DVR, PBS kids live, sometimes Playhouse Disney live, and very occasionally Noggin live. All of these formats share the common thread of no commercials during the actual shows. They all have their own little versions of commercials in between shows, but there are typically no show interruptions to contend with.
This holiday season we've been letting the kids watch Christmas special shows on Live network television, with *gasp* commercials. As soon as a commercial comes on The Girl screams "I don't like this show," and is quite upset, assuming we have changed the channel without her approval. The Boy has caught on, he used to protest similarly, now he just says "it's just a commercial."