"Some people say it can happen but refuse to say what object could cause it other than one individual who stated that a pullover draw string caught on the trigger of a Glock and caused a negligent discharge as an offer was putting his weapon inside his pants. I talked with our PD armorer over the weekend and he said "Horse hockey"! & I agree with him. A draw string is too fexible & there's too much room in the trigger guard for the string to catch on the trigger. If it could happen the person would be a fool to keep on trying to holster when he felt the resistance. I haven't watch the youtube video but I bet it's faked."
I think you may have misread my post. I said the plastic piece attached to the drawstring got caught in the trigger guard. It wasn't the actual drawstring itself. As far as the authenticity of the video goes, it looked pretty realistic to me. However, I do believe this could happen if a piece of plastic were to get caught in the trigger guard while reholstering. I know that guns don't just fire themselves but I also know that a trigger doesn't have to be pressed by a finger to be activated.
