Syntax description file for m3u file format in vim
You can install the m3u (and also m3u8) syntax file in ~/.vim/syntax in many Unix systems.
I recommend you to add # vim:filetype=m3u at the end of your m3u file or the following line on your vimrc:
autocmd BufEnter *.m3u\(8\|\) setlocal filetype=m3u