For the sound, I wonder what the odds are on it trying to play valid, but wrong addresses? or is it hardcoded to an address that will always 'fail' and stop the dma?
In the nicovideo video on stage 3 when the birds are shot sometimes they scream and sometimes they don't. This is the behavior I see with the bus errors working. When the bus errors are off like XM6 sometimes they scream and sometimes the audio freaks out for ~10sec. I guess to to be sure if the dump is bad we'd need to know whether the video is using original disks or not.