[user@myhost ~]$ sudo pacman -Syu --noprogressbar
Password:
:: Synchronizing package databases...
downloading core.db...
downloading extra.db...
downloading community.db...

vlc videofile.mkv --input-slave audiofile.m4a

[user@myhost ~]$ sudo pacman -Syu --noprogressbar
Password:
:: Synchronizing package databases...
downloading core.db.tar.gz...
downloading extra.db.tar.gz...

You just try it. The best organizer I have ever seen. Just unreal =). See for yourself:

Looks like YouTube can recognize sound track from uploaded video: