Are your movies using a higher resolution? Maybe the BioHazard 3 playback code is hardcoded to only accept lower-resolution .sfd files... and/or a specific bitrate. Something like that.
If nothing else, maybe you'll be able to downsample the high-quality movie files to match the resolution of R18's movie files, but still achieve better quality by using better software and better conversion settings.
But I'm really just guessing here.
