There are nearly infinite ways of throwing a grenade. The problem with combining right and left click is the timing.
It's even in the video: The flash at 3:35 did not work.
Can't you also change the timing between when you let go of the different buttons to hit basically anywhere inbetween the long and short throw?
All in all, it's a cool feature but honestly not worth the hazzle of finding 900 different flash combos when you can just take a step back/forth or bounce the thing using the regular right/left/middle throws.