We've seen this before here and in other riots - hiding behind an ambulance while throwing rocks
He also noted that an Israeli border police officer was hit in the face by one of those harmless rocks.
The YouTube videos of the weekly protests are carefully edited to cut out any rock throwing. For example, here's a screen shot from last week's riot, where you cannot see a single rock thrown - but you see plenty of rocks littering the road behind the Israeli police:
