To my knowledge, they haven't sold DVDs of the show. They've sold exercise DVDs with the pro dancers from the show, but that's all.
The only video that seems to have been yanked from YouTube is one of my faves ever, Mario Lopez and Karina Smirnov skating the Paso Doble to the music from "El Mariachi." Everything else that I've ever looked for is there--though just as individual dances, not as the entire program segment.
The one that was yanked was probably due to a music copyright issue. Typically, youtube turns the sound off in such cases and leaves it to the owner of the youtube channel to delete the copy.
A better strategy for the music company is to put up a link to Itunes and sell the song-that is very common nowadays.