That is the question. When a comic starts recording their material for mass distribution - be it through TV or direct sales - they weigh out the pros and cons of putting their "A game" material out there. That's mainly because of the stigma that comics face (and put on themselves) when they do a show and repeat a joke that they may have done on a televised special.
Personally, I don't think it matters - exposure is exposure is exposure. I mean, why is it that comics are the only performers that always have to deliver something new every time? They don't have to do that. As long as the materials gold, what does it matter? It's gold!