Hi there,
Thanks for the detailed report - it's always useful to have as much info as possible!
I'm not sure why you rewrote some of the code like you did, but I think the issue here is the OGG file format. In my testing I did not take that into account correctly and it is causing some feed errors (particularly with the MIME type detection as that is a relatively complicated function.
I'll look into this some more in the next few days and post an update here once I have a fix for the issue.
Regards,
Hugh