"Rules Myths" questions

[TwoBits]

In researching for the document I write out every year for local summer league coaches, I came across this explanation in regarding the myth about a player catching a fly ball and falling over the fence being a homerun:

"As long as the fielder is not touching the ground in dead ball territory when he catches the ball, it is a legal catch if he holds onto the ball and meets the definition of a catch. If the catch is not the third out and the fielder falls down in dead ball territory after catching the ball, all runners are awarded one base. If the fielder remains on his feet in dead ball territory after the catch, the ball is alive and he may make a play. (Except FED in which case the ball is dead and 1 base is awarded.)"

It's the part about the fielder remaining on his feet in dead ball territory being able to make a play that I'm questioning. Is there a resource verifying this? I might add that this explanation was taken from a site supporting PONY league, but I'm interested if this is the official OBR interpretation.