ktech wrote:So what you're saying is, the last gunfight you were in, you were able to remember to use both hands because you've trained so well?

If you have to remember or think, you're already screwed.
People have a tendency of using their dominant hand under stress because that's how we've trained ourselves to hold things. A pen, a knife, a fork, unless the object is large or heavy enough to require the use of two hands, people default to using one. Using a firearm two handed is not a natural activity, and it takes training to program the subconscious to operate the weapon correctly.
Whether LEO or civilian, a person who carries a firearm should train as often as their finances and schedule allow. You want to train to the point that all aspects of weapon manipulation become second nature, and can be performed entirely by the subconscious mind. The same way you can drive a car without having to put any thinking into it. If the situation ever goes bad enough that you have to use your weapon, you want all of your attention on the bad guys and your surroundings. If you have to think about or focus on your gun at all to use it effectively, you're more likely to make tragic mistakes.
I don't want to second guess the cops, but it's pretty apparent from the video that they hadn't trained enough to operate their weapons properly, and they had very little situational awareness - both in their position and the positions of bystanders relative to the target. It's likely that with the necessary training that the number of bystanders who were injured would have been reduced. Their lack of proper training is most likely the fault of their agency, what with budget cuts and all.