Paraphrasing a recent CombatDiver post, after 6 mags in an M4 rifle, the potential to "cook off" rds. is almost certain. Without getting near the trigger.
Catching fire seems worse, saw a similar vid with an AK, both continued to fire, until the flames were too bad.
Great way to ruin a gun, that's why, one needs to celebrate diversity, AR to AK, back to AR, than to FAL, than back to AR,
Pray for back up.