Embedding a song in your thread is actually quite simple. It is just a matter of placing the embed code for a Youtube video in your thread and then changing the height and width of that video to "0" and then just adding the coding for autoplay.
(Credit to Thebluefire2011 for showing me how to add autoplay using BBCode.)
Here's how to do it, step by step:
First, get the usual embed code for your song. It should look something like this:
<flash=420,315>
http://www.youtube.com/v/1orKD1ZG5KU?version=3&hl=en_US</flash>
Like that the song will only play when somebody hits the play button. We need it to play on its own. To do that we must add a little something to the URL to enable autoplay. In between the "3" in version=3 and the subsequent "&" just place this: &autoplay=1. If you do that your code will now look like this:
<flash=420,315>
http://www.youtube.com/v/1orKD1ZG5KU?version=3&autoplay=1&hl=en_US</flash>
Now all that's left is to make video invisible. However, with BBCode we can't do it like we used to do. If both dimensions are set to "0" then the video won't play, unfortunately. Instead we can just set each dimension to 1 and it will be almost just as good. The whole thing will be just a pixel on your screen and probably go unnoticed. The important thing is that it will play. The final result is that your code looks like this:
<flash=1,1>
http://www.youtube.com/v/1orKD1ZG5KU?version=3&autoplay=1&hl=en_US</flash>
Just make sure that you are using brackets in place of the <>'s. BBCode likes brackets.
(Ignore the fact that the URLs are hyperlinked. The system won't let me post them as plain text.)
http://www.youtube.com/v/1orKD1ZG5KU?version=3&autoplay=1&hl=en_US