I have noticed this activity the last few days at this hive. There is always a few bees congregated on the entrance and some of them are shaking. They will do it for a while and stop but there is always some of them doing it. Is this some sort of dance or do I have a problem? Sorry but youtube took out a lot of the graphics.
https://www.youtube.com/watch?v=NOt4vWnVlRA&feature=youtu.be
https://www.youtube.com/watch?v=NOt4vWnVlRA&feature=youtu.be