As it says in the video description
"RC-truck Tamiya Scania with Leimbach roll-off kipper and trailer. Trailer is selfmade with brakes and wireless lighting system.
Servonaut speed controller and soundmodul."
I don't know if this is the same one in the video, but it is one example.
http://www.ss-tronix.co.uk/tamiya-wireless-trailer/