That page has one error on it. Your file named Rammstein - 1999 - Live Aus Berlin-concert.mkv should work, but put it in the Artist folder, rather than the Album folder.
Single-track videos that correspond to a music track should be left alongside the music file, but a full concert, or a featurette, should be up one level, in the Artist folder. I think I reported the error on that page some time back, but it hasn’t been fixed.
I have an example myself that works:
