2 reasons, first they may be wearing the camera (think go pro) so you can film and help. Alternatively you got there a bit late and thre is no room to get invol

2 reasons, first they may be wearing the camera (think go pro) so you can film and help. Alternatively you got there a bit late and thre is no room to get involved so filming does no harm. It is different if the first person on the scene is standing over the injured party with a mobile phone held out to record them without providing any assistance e.g. calling 999/911/112 etc