@aweeks007
Because every game needs a different amount to play the fmv, there's no real sweet spot to set it at. At the time I had it at 250, which gave it a good amount of rewind but clearly was too much for the games I mentioned. Some of them could only take about 50 which is not enough rewind.
The only solution I recommend is to turn it off when an fmv plays then turn it back on when it's over

@mitu Weird, I wonder why it does that? Is there a way for Duckstation to not change the audio?

@barmanphysics Is the save file a STATE save or did you use an ingame save point? If it's ingame, then you could also try the other ps1 emulators, to see if it's related to the emulator you're using. (I'm not 100% sure if you can use save files between emulators.)
I am planning to play FFVII on my Pi but it will take months before I'm where you are now.