CDN Custom Links not changing to cdn urls.

Hey guys, heres my problem. Firstly, in order to solve the problem, I have disabled everything in w3tc except for the cdn. I am using amazon cloudfront, and it works fine for attachments, but I don’t want to host all my attachments on the cdn; rather, only the mp3 files in my uploads folder.
I have set everything up, and under custom files I have the following : {wp_content_dir}/uploads/*.mp3 When I click upload custom files, it finds the exact amount of mp3 files that I have, and uploads them succesfully and I can see them stored in the S3 bucket. The files also are accessable via http

[audio src="https://d2ucjen1j8h8vv.cloudfront.net/wordpress/wp-content/uploads/2013/12/MinorBlues_C.mp3" /]

However, the links inside my wordpress posts, which correspond to the mp3’s are not changing! What am I doing wrong?

Thanks, -Tim