I would have thought the 12xl would be a bit slow, but it definately gives the little truck alot of poke. Wont have to worry about though- looks a bit nippy in that video...
The Bonzer has the gear ratio of a touring car because it's a truck based on a TC chassis, so you need a slow turning motor with lotsa torque to make it run. Using the 12XL is actually one of the best choices for the truck.
It's looks just like a tamiya baja king with twin detonator wheels and tires. I have a baja king and tried mt tires on it, pretty fun. Do tamiya hop ups fit that?