Looks like she had a squib; Always instill proper firearm safety procedures with your fellow shooters!
If you count the rounds, 6 went just fine. It was the 7th where she had the malfunction. If she had stopped and looked at the case that came out when she cleared, she might have realized it was a squib. From the angle of the video you can clearly see there was no exit out of the muzzle on the 7th round, but would be hard to see as the shooter. It was when she put the 8th round in and pulled the trigger that things went to heck in a hand basket.You could see and hear the squib right before it blew, it looks like she had 2 rounds stuck in the bore and then the 3rd grenaded it.
She didn't seem that new to shooting. She cleared the m1 without much hesitation so I am guessing that she was familiar with it. Too bad she didn't understand the situation. So yeah I maybe she was only half trained.Should have known something notright when there was no recoil, like the 6 other rounds fired.
If she was new to shooting, she should have been supervised.