They do, they have to be at WDW (or DL depending on which commercial they did) within 48 hours of the commercial airing. They generally come in the next day, are in the MK parade (as the Grand Marshalls) stay overnight and then leave. It is only the person (or people) that actually do the commercial though, not the whole team.
I'm not trying to be mean, but most NFL players wouldn't say "Boo" for $50K. I gotta beleive that it is worth more to Disney than $50K and a free trip. Saying, "I'm going to Disney World" is probably one of the MOST RECOGNIZABLE post win statements ever!