What I can't figure out is why some felt it was more important to video the distruction rather than lend a hand. There were several videos played over and over on the news of a group of people struggling to clear debris to gain access to the injured, and the person just sat there recording it.
No doubt the NRA will claim if every runner and every spectator had been armed, the bombing would have never happened.
If you have no medical skills you may as well stand out of the way filming. Sometimes reviewing videos of events helps investigators catch those responsible or figure out more efficient ways to respond in the future.