According to the LAPDOnline, who provided the video:
…the desk clerk at a local hotel took notice of a man with a back pack who walked into the lobby and began to suspiciously look around. He asked the clerk about the price of a room, and then pointed a gun at him and demanded money. The suspect walked around the counter where the clerk stood and told him to open the cash register. The clerk, fearing he was going to be shot, opened the register and gave the suspect money.
During the robbery, an elevator door opened, and two hotel guests who happened to be martial arts experts visiting Los Angeles from Oregon for a martial arts’ tournament heard the clerk’s cry for help and immediately took action. The pair grabbed the suspect who was holding a gun in his right hand. During the tussle with the suspect, the Good Samaritans repeatedly asked him to drop the gun and stop struggling. The pair was finally able to wrestle the gun from the suspect and took him to the ground with a leg sweep and then held him on the ground until Rampart Division officers arrived.
As an aside, please note that the MMA guys didn’t use any more force than needed. They restrained him from escaping and/or shooting, but that’s it. Besides fighting against other trained people who’ve signed waivers, this is the way most people practice martial arts in real life, not as short-fused rage junkies. (That said, I do love any flick based upon the former general concept—lots of rainy streets and neon-lit noodle shops, please.) Your unlucky day, hotel robber. Tap out.