Under attack, I think. What can/should I do?

My hive appears to be being invaded by outside bees. My bees have a yellow band on their abdomen while the invaders abdomens are solid black. You can see one to the left to the entrance at 0:20, and another in front at 0:25. A couple casualties out in front at the beginning of the video. Is there anything I can/should do to give my bees a leg up?

Not enough for me to be sure, but obviously you had more chance to see what was going on. Did you see bees wrestling or rolling around fighting? Bees can be very variable colors, even from the same hive and the same queen - she mates with 20+ drones and the color of the offspring will depend on which drone semen she is currently using to fertilize eggs. If they aren’t fighting, I wouldn’t do anything. You already have a nice small entrance.

If they are fighting, I would consider cobbling together a “robbing screen”. This is a nice little article on how to make one. I think you can buy them, but they are pretty simple to make yourself:
http://entomology.ucdavis.edu/files/147611.pdf

It looks like a drone trying to beg his way inside. No worries.

Thanks for the reassurances. I guess I’m being a helicopter-keeper. No fighting I could see - just the two bodies and the fact that there was much more activity than on the other hive made me take a closer look.