Busy as a Beaver

Has anyone watched a beaver while they work?  Our recent "digs" include a pond and 2 resident beavers.  Two large, well constructed damns are constantly experiencing upgrades.  My wife has nicknamed them  -  Burt and Ernie.  We suspect they are father and son as one of the furry creatures seems smaller and more eager to mimic the larger.  These 2 beavers can rest easy as we mean them no harm and thank them for the willingness to be part of the camera's view.