Postby Chad » Fri Jun 13, 2014 8:27 pm
You can't use a URL, you have to use an MP3 file. You can download the YouTube audio through a YouTube-to-MP3 conversion site, which there are several of.
Just put the MP3 file in the same folder as the .lvl file, then input the name exactly in SMBX (plus the .mp3 extension), and click Custom. It should work then.