I think Hmabone is right. If you stop and try and see the wound, it looks like MEAT, not any gushing. I have seen that kind of wound when you send a bullet through your hand, and yes, you can still open and close you hand, you just won't have any strength.
A surface woulnd, though, bleeds like a blown pressure hose. You see that a lot when you have people with meaty hands shooting old 1911s or HiPowers of PPKs pistols. Hammer bite, or in the case of the PPKS, the slide slicing the guys hand lke two razor blades.
Always funny how the serious wound doesn't always bleed a lot, yet the severe one will hardly trickle.
That link also has some other interesting links on misadventures of all kinds.
I would in no way imply that it does not happen like it disd to you. I have just seen enough things where people do nasty things to their appendages. I even near had thumb torn off my hand, and my thumbnail cut and pushing INTO my thinb where the meat pushing around the nail made my thimb look like a piece of popcorn.I can tell you from personal experience that if you get shot through the hand or finger at close range you will have bleeding and pain (after the initial shock wears off) worse than you would believe. Your hand isn't much good for opening or closing or anything else either. I still have problems with strength and mobility in that hand well over 30 years later.
Looks like just that. You can see the foregrip laying on the grounds as he walks away. Looks like the bullet went straight through his hand.It looks like the G18 had a foregrip on the rail, and it came off during the burst.