Im sure someone will correct me if Im mistaken, but wasnt Riva superceeded by moovid (as in same author)?
I dont know for sure, but I have a sneaking suspicion it's no longer possible to register it.
Have you tried FroggerNG? by far my favorite 68k video player. Supports quite a few video formats, even some that have surfaced after it's demise (I guess they share enough in common with other formats/codecs). Best of all though is that its now freely available and you can find a keyfile on aminet.
