The video of the incident is short: about 1 and 1/2 minutes. It shows a fairly typical method for mentally "disarming" a victim, used for muggings, car jackings, and, as here, home invasion: the use of someone feigning distress or need. In this case, the female came to the door, asking for assistance and requesting to use the homeowner's telephone. Probably one of the things to foil the attack was that the homeowner's dog went outside and, although not shown in the video, probably approached one of the men hiding in the shadows. In any event, three armed men (including one with what appears to be a rifle) suddenly charge the door. Fortunately, the homeowner was able to pull his storm door shut. The suspects then fled the scene.
The takeaway, of course, is to be careful of opening your door to a stranger and, especially, at night. Check through a window or peephole before opening a door, and have sufficient lighting so you can see who is out there. If you have a storm door (like the homeowner here) or a security door, and you decide to open you main door, I would advise that you still keep the storm/security door shut and locked and speak through that door to the person outside.
Of course, this is a case that should serve as a reminder to home carry. However, I would like to point out that simply by retreating into the home, the homeowner was able (in this instance) to avoid any gun fire. That is generally preferable since the legal consequences of shutting the door in someone's face is generally less than having to shoot that person. Nonetheless, if the perpetrators had decided to continue their assault, the homeowner might have had to resort to a weapon to defend himself.