Re: Some Sick Bees video. What is this???!!
Bees in a hive badly infested with varroa can have that cleaning behaviour, but not the diarrea. Diarrea like that can be caused by Nosema Apis, but that wouldn't cause the cleaning behaviour.
So this is a guess, but I'd go with poisoning, most likely a synthetic pyrethroid. Impossible to know for sure just by watching a video though.
Not much you can do, other than wait, and it should pass. You could also note the date of this in your bee dairy, to see if it happens again & is a seasonal thing, in which case you could attempt to identify possible crops that may be getting sprayed while in flower.
I do bee removal work, and some people ring because of a bee problem, when I get there it's bees in a flowering tree or bush./ I explain they are just harmlessly gathering food, but surprisingly often the people will want me to spray the plant to get rid of the bees. Of course I don't, but I know some pesties would.
44 years, been commercial, outfits up to 4000 hives, now 120 hives and 200 nucs as a hobby, selling bees. T (mostly).