I pretty much hate all the commercials they show during the Nats games at this point because they keep replaying the same handful of low-budget junk over and over and over and over and over. My least-favorite is probably the commuter one that looks like it was produced by a community college video production class. Also hate the two guys on the ski lift, icelandic mud, and the dork who decides "hm, I guess I'll have a son and I'll name him Brian." I hate that commercial for so, so many reasons, and I really hope that they'll stop playing it now that Mother's Day is over.
The commercials that really make me furious though, are the ones they insert into the mlbTV streaming video archives. They disabled the clunky fast-forward option recently as well so there's no escaping them. I'm paying $25 a month for this service so how do they justify forcing me to sit through the extra commercials? grrr