Not sure about a clip, but basically, there was a chair by the exit and every time a new dog would become first in the class (even if temporarily) the owner replaced the old 'first' dog/owner. The rottie was on a lead by his owner. A gsd finished the course and upon finishing ran up to the rottie before the gsd owner could grab her dog. The rottie kind of lunged, the rotties owner sort of kicked the gsd away and the gsd owner grabbed her dog. Really that was it. I had a front row seat and saw it reasonably well but it was super quick.
Some of the Facebook comments are just ridiculously horrifying. A bunch of supposed intelligent purebred dog owners jumping on the "Rotties are vicious and shouldn't be trusted out in public" bandwagon.