The big studios do it but the smaller producers don't seem to. I don't - there's a link on the site that covers that. besides, if an affiliate, like a tube or blog, is going to use the video then they would (should) have a link back to the site with the 2257 link on it.
Then again, having it in the pre-roll may make it look more "professional" to surfers used to the Reality Kings and Brazzers of the world. I'd A-B test it.
PS: Attorneys ALWAYS say CYA in EVERY situation so I'm sure one would say include it, just to be safe.
