My first thought about that video was that it really emphasizes the absurdity of the original Bowie/Crosby collaboration. Ferrel and Reilly made it hilarious simply by faithfully reenacting it.
I didn't think it was funny at all; I thought it was a dumb idea.
The original was bizarre enough on its own, I don't need two people re-enacting it just for re-enactment's sake. I didn't need them pointing out how weird it was by redoing it.
Alas, an internet joke I cannot get behind. I must be getting old and cranky.