Bees nibbling?

[Etton]

Don’t look at the pics , just listen!
I have heard this noise before, from the bees anyone know what they are doing. Sounds like teeth chattering!

 

[Finman]

Cannot listen. Too complex to open.

 

[Anduril]

https://beekeepingforum.co.uk/threads/interesting-crackling-sound-from-hive.1999/There is also a YouTube link in the thread

 

[Curly green finger's]

Bees moving