Here is the video:
YouTube - University of Cincinnati Mascot Arrested During Game (Video)

And a link to an article:

“He was throwing them at the crowd and so of course, people threw back and missed him and hit other people,” said UC Police Capt. Jeff Corcoran.

“The officer asked him to stop and he took exception to that.”

At one point, Garfield shoved the officer and both ended up on the ground, he said.
I've heard some say the mascot slipped and did not shove the officer.

Another feather in the cap for Cincinnati police.