Don't get me wrong, flashlights are useful, and I always carry a super bright little one. But it is more for finding and escape route. Definitely it could be useful to blind an attacker. But in the Aurora case, it just seems he would've trained his fire and sprayed wherever he saw the light coming from. Aiming a flashlight at his eyes while he was reloading would be safer, but it would probably just help him see his reload easier, because he wouldn't be looking directly into the light.
The only option I would consider in such a case is returning fire, and/or fleeing.
While I agree that returning fire is much more useful, the people in that theater didn't have a firearm. The point Mr. Webb is trying to make is that you will never be denied (anywhere) the right to carry a flashlight, which is very useful. While I don't own one, my cousin and uncle who do own one (TLR-1 I believe) have showed me first hand what it's like to be on the other side of it. Trust me, it will daze you and you cannot see where the light is coming from.
Imagine looking into a spotlight from 5 inches away. All you can see is light. Also, in a dark environment, having a light shined into your eyes takes away your bodies night vision for a few seconds. Any type of white light will do this, but these high lumens flashlights are remarkable at stunning right away. The first thing I did when it was shined in my face was cover my eyes. I couldn't see anything and when he strobed me, I just wanted it to stop.
If you're using your flashlight to find an escape route in a situation like Aurora, you're painting a target on yourself. If you're moving in the darkness, you're a hard target to spot and shoot at. If you're moving in the darkness with a light, you're giving away your position and drawing attention to yourself. If you're able to blind and disorient the attacker while moving to your exit point, you're likely to make it out alive. All of this is simple training. Don't use a flashlight to light up the room and show the attacker who is where and doing what.