Advantages / disadvantages of freecoaster and cassette hubs
My son wanted to change his freewheel/cassete hub to a freecoaster hub so I did some research about 6 months ago and found this great YouTube video from Odyssey and RideBMX magazine all about freecoaster hubs.

As you said, the cranks will not move when coasting backwards. For my son, this is the real advantage and why he wanted the hubs. Landing a 180 out of a half pipe, his freewheel hub did not allow great control of the bicycle requiring him to spin cranks as he rolled backward (just like that trick at 3:08 in your video).

In the end it came down to money and we (he 12 year old) did not want to spend the money to get a new wheel with a freecoaster hub, you cannot just swap the axle/mechanism/insides of your freewheel shell with a freecoaster mechanism, you need a shell/hub that supports the freecoaster axle/mechanism.