Most of your are familiar with post tags, such as the [Media] tag. This can still be used, and works with MP3, YouTube, SoundCloud etc, but for whatever reason the good people at Invision (makers of the software) decided to remove the button from the post box.
The newer streamlined way to add media is to just actually drop the link into the post. No tags required.
So if you wanted to embed a soundcloud player in your post, just simply drop the link to your player in the post ie
or if you want to embed an MP3 player in the post, just simply put the link to the MP3 ie
Same with YouTube clips. No tags required
The new version of SoundPunk inspects your post just after your post it for a series of media matches. These include mp3 file extensions, YouTube URL's , SoundCloud URL's and more. if it matches any in your post, it will automatically wrap the link in media tags so you dont have to.
Please let me know if there's any questions