There's a ton to the story that folks will never know, but the short of it is the local caddie had a total brain fart.
I would be interested in knowing exactly what happened; have only seen the clip where the guy is doing something with his had to the sand. Don't know what led to this, whether the player had hit his shot from the sand before, or the reason for him doing this.
My understanding of the rule, in reference to jeffwarne's example, is that if the caddie raked the bunker away from the area and line of play simply to tidy up the course, even before the player hit his shot, there is no penalty.
As golfers, we make any number of mistakes in most rounds- bad judgement, brain farts, just plain poor execution. A clear thinker would accept that a caddie will also make a mistake. I don't know the facts, but might the player have been a bit more vigilant? Assuming that the player had not yet hit the shot, what was the caddie doing in the bunker anyways?
A funny caddie story: I have a late tee time in the Columbus District GA Open at Muirfield Village back in the late '70s. The caddie master had run out of caddies and he was only able to recruit a young 10 or so year-old boy to carry my bag. Play was so slow that we went off an hour after our scheduled tee time and the pace of play was around six hours. There was a two or three group backup on 9 tee, so I sent my caddie down to the bottom of the hill on the left to forecaddie. Apparently he got bored, set my clubs down, and started chasing the wildlife.
When the tee finally cleared, I hit a 3-wood down the left side, figuring I'd find my ball at the bottom in the light rough at worse. I get down there and there is no ball, clubs or caddie to be found. A five-minute search found my clubs in high rough some 30+ yards in the woods near a creek and the young caddie playing along the banks, but no ball. My round was not in good shape by then anyways, but having to walk back to the tee where there were now two or three groups glaring at me was not fun. As I recall, I hit the ball again in a similar line, hit a provisional, found my first one in the light rough, and managed to make my 6. I doubt that the boy remembers his initiation into the caddie corps.