I am still not totally convinced in this particular instance that the ruling is correct. Don't get me wrong , I understand the rule & have no issue with it. If I was the rules official and Mr 1% were to report to me what had happened,Without the aid of video I could only listen to the evidence & probably give the same decision as was made at the time.However If I was playing with someone who had this situation.( as in the video.) occur & I witnessed it I would still suggest that the leaf ( A very small leaf.) did not have sufficient mass to cause the ball to deflect & that the deflection had been caused by the gust of wind & the fact that the ball was travelling across a slope.
The fact that the leaf struck the ball does not mean that it must have been the cause for the ball deflecting
the beauty of physics is that it doesn't need to be the leaf hitting the side of the ball to make it move, you are 1000% correct that a leaf would not have the mass or energy to bump a golf ball sideways.... but, just like how a spike mark is enough to deflect a ball off its line at the speed of those putts, if the leaf blew in and became wedged under the ball and the friction between the leaf and the green was enough that the leaf became a stationary as it hit the ball, as the ball now rolls over it the ball is not going to hold it's line.