YouTube comments suggested the attackers were hired by a Super PAC created by David Brock. After a few searches I found the following:
- Wall Street Shill: "Animal Rights" Group Harassing Sanders linked To Obama Admin, Accused Of Abusing Members.
- Direct Action Everywhere protesters attempt rushing Sanders on stage: Clinton smear attempt?
- ... Nothing else
So far I found nothing that directly links the animal rights group to David Brock, the DNC or any political organization. The last paragraph of the Wall Street Shill article confesses the link is entirely speculation.
The group Direct Action Everywhere, an animal rights group claimed responsibility for both attacks. More pics available at Daily Mail.