That is the obvious connection. The interesting part is does Redtube sue them for trademark infringement? Who gets the "red" and who gets the "tube" ? :-)
Frankly I'm surprised Google hasn't preemptively gone after them for infringement.
Facebook sues people for Face* names. Not an entirely unprecedented precedent.
The real problem is you never know when you'll be sued for going too far. The only way to find out is to go too far and hope it doesn't happen. (like, the existence of YouTube itself)
Ah yes. I may have inadvertently typed almost by habit o.O
and now I will try to distract the reader by mentioning something about keystroke dynamics. I wonder if I type pornhub in a different way than any one else does