I will come back later with videos (can't post them from my current work computer) but I have the Covers channel on SiriusXM saved as a favorite because I totally dig some great covers.
A few that I hear from that radio station that I have thoroughly enjoyed and will try to post video for - Florence & The Machine's cover of Halo, Sia's version of Unforgettable, Gym Class Heroes cover of Under the Bridge, Willie Nelson's version of Just Breathe, Kelly Clarkson's cover of Give Me One Reason (Tracy Chapman), Grace Potter's cover of Tush.
I'm sure there's more that will come to me, and many covers I have seen at concerts that I'll have to see if I can find any youtube coverage for.