The reason this was an "oops" instead of a "OMG!" was that he was at least obeying rule #2 and perhaps rules #1 and 4. There is more than one rule so as to provide a back up when we inadvertently botch one of them. I think most accidents do not have a single factor -- there is usually series of factors, of which one becomes the straw that broke the camel's back. The trigger finger rule is a biggie, and if we could be absolutely positive that we could follow it all the time, we would not need any of the others. But we're human, we can't be absolutely perfect, so we do need some redundancy.
The pistolero in the video should probably also review some basic life rules, like "look where you are going."
