Aren't you the one implying something wrong was done in the video? If nothing's wrong with it, then why not let it be seen?
The arguments seem to be varied here... and this one you just put forward seems to admit that something wrong happened. Well, if something went wrong, why defend it as "standard operating procedure" and not admit it was a screwup!?
Personally, I suspect this Marine was unaware that the man he shot was a previously captured prisoner, and he didn't hear or listen to the cameraman telling him that. Honest mistake, likely. Also, perhaps it's someone else's fault if those captives weren't searched. Or if they were, that it wasn't communicated. We just don't know. So IMHO, we shouldn't fry the cameraman, nor jump to the shooter's defense, prematurely.
YOU go search them....