I've looked at that video afgain and again and I could be wrong but I don't think it fired out of battery.
Watch the video, the brass is ejecting too the 1 to 2 o'clock positon
until the shot at the 11 second mark. That brass did not eject or it ejected to her 5 o'clock position. The gun does not fire, she retracts the bolt, either clears the fired brass or clears a lose round from a short stoke, chambers a round (and at this point the bolt looks closed) and boom. It really looks like a squib to me. but heck what do I know.