Why the hell didn't they just drag him out instead of tasering the guy over and over?
Seems excessive to me.
There were both there. The guys with tasers, UCPD, are actual police officers. Lots of bigger Universities do this (like UTPD here in Austin).
The timeline according to the school newspaper article that I read online went like this:
1.) The rent-a-cop performs a search of IDs, the student is found to be without his BruinCard and is asked to leave.
2.) The rent-a-cop decides that the student is not leaving quickly enough, and calls UCPD.
3.) UCPD arrives within 2-3 minutes, the student has already begun leaving.
4.) UCPD finds the student walking towards the exit of the library, and a UCPD officer grabs the student's arm.
5.) The student does not respond well to this move, starts telling the officers to let go of him and makes his body go limp.
6.) This is where the video picks up from.