I am sorry but the application of bernouli's theorem top the ping pong ball example and also to aircraft flight is completely erroneous. Air moving in an air strean has exactly the same pressure throughout. (Check many corrections on the internet for this effect).
The reason the balls move together is that the Coanda effect causes the air stream to follow the curve of the ball which gives the air a component of accelleration away from the centre - because air has mass Newtons laws requires a force to be responsible for this component of acceleration and it is this force which draws the balls together. The same explanation applies to the upper wing surface of an aircraft
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