Very few examples of Japanese developed games used more than 1 palette for FMV. (Game Arts was one of the exceptions and, interestingly, did so with the very first example of FMV on the system -Tenka Fubu- which seems to be fairly similar to Sewer Shark and Night Trap)
It seems to be the exact same framerate and audio quality as Tenbu MCD Special, but with the frame cropped horizontally from 240 down to 192 pixels. (the intro portion also seems to use the same dithering scheme as Tenbu -different from Road Avenger, which has a lower color threshold and looks much more like typical floyd steinberg dithering)
Albeit, at that quality (240x160 16 colors 6.3 FPS), Tenbu would still have the bandwidth for 32 kHz PCM, but it definitely doesn't sound even close to that. (and that's assuming the data rate is actually maintained close to the 153600 bytes/s peak for mode 1 data)
So, given it's 16 colors per frame andassuming 16 kHz PCM, that would allow the same screen size and framerate as Road Avenger (7.5 FPS, or one update every 8 NTSC video frames), or a higher framerate at the 192x160 frame size. (doing 1/7th of 60 Hz would give ~8.6 FPS and should fit the bandwidth)
We were talking about trying to use paired channels for higher res (perhaps 13 or 14-bit) output via the ricoh chip here:For Sonic CD FMV audio, I think the original FMV 32KHz 8 bit mono would suffice since 8 bit mono is the easiest to use for SCD FMV.
If that did work, you could do 8-bit ulaw, ADPCM decompressed to high res, or uncompressed high res PCM (though that would waste bandwidth). Of course, any such use of the ricoh chip would require double the buffer space in wave RAM (or more frequent updates of smaller buffers), so doing it Sonic CD style (32k double buffered and updated only once per second) would limit that to 16 kHz mono, but obviously you could do much more with smaller buffers updated more often. (albeit, at the expense of more overhead)
But yes, the existing 32 kHz PCM renditions are pretty good in any case.