I did not work directly on MAFFS but I did "support" a couple MAFFS missions. I was an engine and propeller mechanic and went along to help with other tasks such as operating support equipment, washing the retardant off the plane (it's corrosive), etc. The MAFFS missions took a back seat to middle east deployments after 9/11/2001.
They are the dump truck or delivery van of the aircraft world and are modified into all sorts of neat variants. In that video they were flying a C-130J, the newest version. I worked on very old C-130E aircraft.