That's in reference to the concept of "us helping the poor" as opposed to "us helping us."
You can find the entire video here.
I think people like the turn problems into an "us vs. them" fight because that justifies doing terrible things to them. They're a separate group- a group that is subconsciously inferior, even though they're not inherently better or worse. They're just in a different situation, and at a different stage in personal (or, in the case of groups, group-al) development.
But if it's "Me vs. Her/Him/Them," I can do stuff to them that I would never do to someone I classify as part of "us" (which is really someone I classify as part of "me.").
Although I (or whoever the "us" party is) know consciously that a given action/thought/attitude is wrong, the "us vs. them" complex allows me/the us party to ignore that conscious knowledge.