whats in the video_rm folder?
Video_TS is always on DVD-Video discs. _rm I’m not sure.
Honestly the best thing to do, would be to make
a vhs dub of the content with a timecode window if possible,
then capture that and do the music synching that way.
This type of thing is called “sweetening”
then when your done, export your audio track and author another
dvd with the video streams content ripped from the original
disc, then lay down your new audio track as the audio and your done.
thats the best way to do it and maintain picture quality.