Not having a place to sleep at night, especially one you've specifically reserved and paid for, is a very stressful situation. The stressful situation elicits a stress response and gets directed at the clerk, who responds in kind.
I don't have enough context to say this guy is super entitled or not (but it is reasonable to feel entitled to a room you paid for). That said, just going off the video, neither the clerk nor the customer are to blame. The clerk's hands are tied and the customer has to quickly find a place to sleep for the night.
You're right, though, the real problem is the owner. If a hotel was providing a lesser service than shelter, I would agree with you about the customer, but in this case the problem doesn't fall squarely on the customer's shoulders to me.