If you had watched the video or read up on lasers, you would know that you don't have to trust your life to a battery. If the dot were not to appear, you would simply use the iron sights.
If you use the laser as an instructing tool, your life is not likely to hang in the balance, anyway.
If you don't want to trust your life to a battery, I hope you never need to be fitted out with a Pacemaker. ( LOL)
You can order the Crimson Trace Video, "Shots In The Dark" ( approx. 75 minutes ) from Paladin Press - Publishers of the Action Library
but Crimson Trace has been known to give it away to prospective customers. The company can be found at Crimson Trace: Laser Gun Sights For Shooters
I do not own a laser but I do have a set of tritium night sights. I consider the tritium sights a waste of time, having tried them out in a darkened room and had a hard time telling which dot was the front sight.
It is good to be skeptical of new technology. Still, it pays to check that technology out with an open mind. NOTE- Not long ago, the military thought scopes were only for sniper rifles but today, they are on every M-16 and troops are hitting their targets.