Not to argue with the premise--I have no issue with LEOs or others using a real firearm when threatened by what may or may not be a toy firearm--but...
In typical media fashion, the video shows a couple of rubber caps put on the threaded muzzles of AK barrels. Not AK rifles mind you, but barrels/gas blocks/tube assemblies of unfinished parts kits. Technically not even firearms per the ATF. They were probably put on there to protect the threads and in this case have absolutely no relationship to the "story" they are trying to put forth.
ETA: and now after posting this, I read through the comments at the link where they say the same thing. Oh well.