Take background Music from DVD's.

You can't. Some DVDs feature the musical soundtracks as stand-alone features, though.

 

I was really excited the first time I had a DVD with that extra. The DVD was Amadeus. But I hate the fact when the scene ends so does the music.

 

I wonder if there is PC software that allows you to seperate and filter tracks. Then allowing you to record back just the musical score.

 

This is like my friend who figured there just had to be a program which could automatically turn a wav file of music (guitar, bass, vocal, drums, keyboards) into a .mid file! LOL!
The only real way to do what you're asking would be if the stereo tracks featured no dialog and only music (dialog contained to the center)- you could extract just the R/L channels but you probably wouldn't lose sound effects in that prcoess (as they are in the l/r usually as well).
You have to understand that these elements are not seperated in layers or anything- rather all in one single audio sound. It's like asking to remove only the guitar part from some rock song you have on CD, without affecting the Drums or vocal... Unless you have the multitrack stems for the recording, this would be difficlt, if not impossible.
It would be a billion times easier to buy the soundtrack CD.
-Vince