I will give you my take on what I saw on the video. To start with the referee is far too casual. No foul. The UCSB player had already kicked the ball when the UCLA player came through and made contact with the UCSB players leg. Once the Ref decides a foul has occurred there is nothing wrong with the Referee stopping the clock for the foul, especially if he thinks the UCLA player may have been injured. But, the referee never goes to check on the UCLA player even though he is still on the ground holding his head. Any possible or perceived head injury should have had the trainers on instantly.
Now is when some of you will not agree with me. The clock is a big deal in college since once it hits zero the game is over. So now think like a referee. The foul is called not when the whistle blows but when the Referee determines a foul occurred. It took approximately two seconds for the ref to whistle the foul and indicate "stop the clock." So, I can understand the Ref's justification for adding 2 seconds back onto the clock, but not 5 seconds. So, if he was going to add time he should have added 2 seconds. If you watch the Ref he blows the whistle to restart play and the clock and it takes 3 seconds for UCLA to take the kick. Had the Ref only added the 2 seconds then the clock would have hit zero and the goal would not have been scored.
IMHO the whole thing should never have occurred because there was no foul. UCSB did not protest the foul call, because judgment call are one of the things that cannot be protested. Hopefully they did a good job with the protest write up.