Hello, in fact this one is particular because it is a midi file which I opened in the software BAND IN A BOX and clicked on the transform feature which tries to transform the midi file in a standard BIAB songs. So it makes transformations, tries to identify the chords, the melody, etc. And adds a rythmic/drums.
The result is a standard BIAB song, which sounds a little bit like the original but is quite different from the midi file, in the instruments and sounds.
I then played it by muting the melody track.

What you can do is find the midi file and play it without transforming it, you can sing while the melody is playing. That's all I can say to help you, it's true that I couldn't find a karaoke video of la supplique pour... on youtube.