1. It does so because you allow VLC to take control during the installation process. NEVER click next, next, next... automatically. Read before clicking.
2. If you can, NEVER install applications on Windows OS. Use portable versions (there is a portable VLC version).
3. reinstall VLC without file associations or uninstall VLC and use the portable version without file associations.
Portable VLC : file type 7z, zip
Win 32 :
http://download.videolan.org/pub/videol ... ast/win32/
Win 64 :
http://download.videolan.org/pub/videol ... ast/win64/