This is an interesting video. Up until a few days ago I have never heard or seen this beach in the Marietta islands near Puerto Vallarta In the last few days it has popped up over 20 times on different blogs, I even saw one from Japan
It seems this beach is a natural phenomenon and the conditions have to be just right for it to be used. The tide, moon and winds have to be just right and then you have a beautiful secluded beach.