Hello, there's something weird for me when i bought this game, i didn't had the music so i have read this topic to get the soundtrack that works and thanks for that because it works, but an other problem remains, in fact i had two problems with this game, the sound first, but the 2nd problem is that when i start a new game i don't have the intro with the cinematic (the kind of cartoon with the music and the storyteller who tell the story..), the game start directly with the map... I don't know why i have this problem... Thank you if someone can give me a solution to fix that problem...

The is not part of Rayman Forever.
However it's available as game bonus in .mp4 format.

This is a direct port of Rayman Forever. It includes the following:
Rayman
Rayman Designer + Mapper
Rayman by his Fans

It does NOT include the following:
Rayman 60 Levels
Rayman intro movie

The soundtrack is also incomplete, thus it has to be replaced to get the complete one.

They're not. If you check the file sizes you'll see the original files are missing large portions of the music.