Did the Japanese pay for the RIGHTS to do that?

Somehow I doubt it. It was a Japanese TV show called APE CORPS that somebody cut into a feature film (TIME OF THE APES) and released it over here. When it was made, around 1974, it could be a smash hit in Japan and no exec from 20th Century Fox would ever have known about it, plus in those days, most companies were a little less paranoid about intellectual property rights as they are now. The first time I recall a legal situation arising was when Universal sued distributor Cinema Shares over calling GODZILLA VS. MECHA-GODZILLA, GODZILLA VS. THE BIONIC MONSTER, which was a decision made by Cinema Shares, not Toho.