A recent job for a client had us building a blog and a podcast, not that unusual for a modern site. However, we noticed a small issue, the podcast would load properly on a PC, you could load the audio file directly from the site, enter the feed into iTunes from the site, or subscribe to the podcast directly from iTunes, but not on a Mac.

We did a lot of research, both online and off, and couldn’t find a solution, everything looked correct. As we were using Feedburner for the podcasting feed we tested and retested the feed using the large number of tools available from Feedburner.
Nothing.
The feed was valid.
Everything was fine.
Then it struck me, I was looking at the XML for the feed and noticed that the filename for the audio file had spaces in it! This was in the URL for the audio file for the feed. Feedburner wasn’t encoding the spaces to the expected %20, they were just spaces.
I quickly renamed the file trading hyphens for spaces, reset the feed, waited for iTunes to sync up, about 5 minutes. And like magic everything was working perfectly on a Mac.
I can’t tell you why this feed with the spaces works on the PC version of iTunes and fails in the Mac version, but if you ever run into this problem, check your filename for spaces.