i think the cms always sound abit better, or abit different
you gotta admit sometimes her live performances don't sound exactly like her albums or cms, but it's all natural 'coz ayu's human.

but i guess the company that ayu is doing a cm for would want the cm song to sound the best that it can, i mean.... who would wanna watch a cm that the song sounds very bad? (not that ayu is a bad singer, she's GREAT :))