guy in the video didn't look like he trained much. no offense to the dead, but he did not look confident in his abilities with his firearm at all. training could have made all the difference in that situation.
He could have emptied his mag into those guys before they even got to him
1. The gun is always loaded.
2. Never let the muzzle cover anything you are not willing to destroy.
3. Keep your finger off the trigger unless you are ready to shoot.
4. Be be sure of your target and what is beyond it.