these assets can be used in game for something else.
example: build a shoe for a commercial. use the shoe in the game aswell.
or build a car for the commercial - use the car in the game aswell.
the car and the shoe must had been build anyway..
another one: build a character model for the commercial. use the character model for the game aswell!
something more different: build a sound for a commercial. use the sound in the game aswell!
hah?
another one: build a city background for a commercial. use a citiy background for the game aswell!
watch how this goes... maybe theres another one?
while not all assets from the commercial might be 100% useful or top priority to build right now - many of those are and those that arent increase the depth. and with those other points Nowak mentioned its clear thats its pretty efficient!
I have another one: Build a Design for a company Logo for a commercial. use the design for a company logo in the game aswell!