I think the rules on this are quite clear. See www.wpa-pool.com.
A story I've told before: at the 1976 World Championships (in Asbury Park), the off-brand tables had plastic-coated wire runners to take the balls to the ball hopper. The problem is that the wires came out to the bottom of the pocket rather than being joined to an L-shaped pocket. On many break shots the object ball went straight into the center of the pocket at speed, hit the wire runner and trampolined back onto the table. End of inning.
As for the video of first one guy and then Efren being treated badly by the same pocket, the moral is same as for the Asbury Park event: don't play on lousy tables.
A story I've told before: at the 1976 World Championships (in Asbury Park), the off-brand tables had plastic-coated wire runners to take the balls to the ball hopper. The problem is that the wires came out to the bottom of the pocket rather than being joined to an L-shaped pocket. On many break shots the object ball went straight into the center of the pocket at speed, hit the wire runner and trampolined back onto the table. End of inning.
As for the video of first one guy and then Efren being treated badly by the same pocket, the moral is same as for the Asbury Park event: don't play on lousy tables.