Ouch!
I feel very vulnerable in the 777 when taxiing round JFK... With the A380 this sort of thing seems inevitable, unfortunately.
From the video clip, it seems that the anti-coll. was active on the RJ, even though no taxi lights were on. Maybe being marshalled by someone out-of-shot?
If it was occupied, must have been quite a shock (and lateral acceleration)...
Edit: It looks like it had just arrived and wasn't quite parked, hence a probable reason for the collision...