I've read a post about AI Servo and AF Back focus button but I noticed that when I attached an external flash it won't fire an assist beam, is there something wrong with my setting or 7D does not fire a beam when on AI Servo mode?
Assist beam only works with one shot mode, and its completely logical, because ai servo is a continuous focus track, and for that you should need an assist beam what is always on, but its not possible, so... Get used to it : )