Everyone knows what buck shot can do... An AR is still a great home defense weapon and has many uses.
Also if you ever had a hostage situation that you needed to be 100% accurate with a shot, using an AR you could easily place a round in someones head without hitting the hostage at ranges inside a house. You could not do that with a shotgun and that is an extremely scary shot with a pistol.
That second video is so amazingly ridiculous it isn't even funny. The chick somehow managed to fire 5 rounds of 12ga 00 buck in 3.59 seconds... so .72 seconds per shot while transitioning with a heavy recoil gun. But with the low recoil AR she can somehow only fire 1 round per 1.33 seconds... Stupid.
A good shooter with an AR could have put 3 rounds into each of those targets in 5 seconds or less. People that are highly efficient shooters could have done 5 rounds into each in 5 seconds or less.
I don't quite get the 5 rounds either 1 well placed shot with maybe 1-2 follow ups to make sure would be good.
Good home defense rounds will not over penetrate and deliver plenty damage contrary to belief.
http://www.hornadyle.com/products/rifle-ammunition/
click on a round and then click on gelatin on the table.
Edited for lazy people
^55 grain tap urban, 5" cavity, max cavity size is at 5"
here is a 60 grain, 5.25" cavity, max cavity is at 6.25"