You’ve run into one of the fundamental problems with how WordPress natively handles media enclosures (podcasts) on a per post/feed item basis. The short answer is, you should only have one media episode (file) associated with one feed item (blog post) in your blog’s feed. You ‘can’ do what you’re doing, but it is never going to work, at least not with iTunes and nearly all other podcatchers and podcasting directories.
There’s no way to tell iTunes to combine media files via your podcast RSS feed. Such a feature would be pretty cool, but also impossible. For example, if you put both an audio and a video file in your blog post, would you expect iTunes to append the video file as audio or would you expect iTunes to convert the audio to video and make one large final video file? Video is another huge complication, factoring in frame rates and formats, it would require a lot of time and processing power on the clients computer just to combine the final product.
Each podcatcher (such as iTunes) and podcasting directories handle multiple enclosures in feeds differently. iTunes will download the first enclosure that it sees in the feed ignoring the rest. Other podcatchers and podcasting directories either pick up the first enclosure or the last in each post item. Because of this inconsistency, Dave Winer (the creator of the RSS 2.0 specification) does not recommend multiple enclosures. You will find that when you validate your feed at FeedValidator.org, Feed Validator will warn against it as well.
The Blubrry PowerPress plugin is the only WordPress podcasting plugin that prevents you from adding multiple media files, so you can’t accidentally make this mistake. I’m not sure why the other podcasting plugins don’t take this much care to make sure your podcasts are accessible to the largest number of podcatchers, applications and directories as possible.
In your case, the solution may be to use an FTP client to upload your large mp3 files to your Godaddy server. Otherwise, you may need to look at other media hosting options or add each media file to separate blog posts.
