Two clips, the second from Dave Weigel who was on the scene:

“Do you have credentials to cover this conference?” asked Clayton. “No,” said Breitbart. “Maybe you should leave, then,” said Clayton. “Okay. If you want to get someone to escort people out of your conference, there are progressives at…” “So it’s okay for you to be here without paying?”… Breitbart moved on and attempted to enter the main hall of the conference; he was denied, because organizers had denied him press credentials. Clayton followed; Washington Times reporter followed with him, asking Clayton who he was asking Breitbart about. Breitbart quickly decided to head upstairs, chased out by cries of “Coward! Coward! Coward!”

He walked into the online left’s biggest event of the year and, per Weigel, was apparently set to enter the main hall knowing that every liberal there hates him with a passion. The organizers blocked him, then people started screeching accusations at him about using coke and sleeping with prostitutes. So he left. Yet somehow, in the progressive telling, it’s Breitbart who’s the coward. The saddest part, via the second vid: Actual high-fiving after he was gone to celebrate the total pwnage of … denying a guy press credentials so that he can’t confront you on your home turf. Take that, wingnuts.

Update: Breitbart tells Mediaite that not everyone at the conference was as belligerent to him as the people shown here: