I figured out how to get the Soundcloud plugin to work: You have to use the following URL format:
http://w.soundcloud.com/player/?url=https://api.soundcloud.com/tracks/<track ID number>166877736
I don't know why vbgamer45 used that syntax for the Simple Audio Video Embedder mod, but this is the URL that is used by the Soundcloud embedded player thing when we share tracks.
In order to get the URL above:
1) Go to the song page
2) Click the share button
3) You'll see "Share Embed Message" at the top. Click "Embed".
4) Copy the track ID from the URL in the HTML code they provide and append it at the end of the URL above instead of the <track ID number> thing.
THen it should give something like this: