It's called running subsonics through a semi auto pistol. Not enough ass in the low power rounds to cycle the mechanism. Certainly not a pro.
He was definitely an average guy, but the thought to go with subs and a suppressor makes him a firearmsish guy. My bet is he didnt get the suppressor booster installed all the way, or he fucked something up cleaning. That being said... He's practiced tap-racks before.
I had a .380 ruger pistol that would not cycle if you limp gripped it. Gun was given away to me since they thought gun was bad. I brought it to the range and had no problems. Told the ro and he told me about that problem and was able to duplicate by loose grip.
You can induce that with most pistols on the smaller side, particularly browning tilting barrels, it's just the physics. If you watch the video, shooter ain't limp wristing. What he's shooting I can't tell, but I'm just waiting for it to turn out to be a "ghost gun" 🙄.
I used to have a single stack sig pistol that would do the same if you let your grip relax too much. I ended up trading it for something else out of fear of the gun failing to properly cycle in a life or death situation.
Certainly not a pro.
It's rough out there. Sometimes you have to save some cash and DIY.