Please describe the problem:
Several podcasts I listen to have the same file name for each cast. For example http://feeds.theonion.com/theonion/radionews. The files all get labeled as "podcast_redirect.mp3". The old casts are (mistakenly) overwritten. 

Steps to reproduce:
1. Add http://feeds.theonion.com/theonion/radionews to the podcast list
2. Play one cast.
3. Download the next pod cast.
4. Play the first again, it will be the new cast.


Actual results:
The audio is of the second cast, not the first

Expected results:
It plays the original podcast. All podcasts are named uniquely.

Does this happen every time?
Yes, if you follow the steps.

Other information:
Have a list of steps the plugin goes through to name the file uniquely:
1. Using the 'link' tag.
2. By using the HTTP 'filename' header. 
3. Serial Numbering.

As more cases arise, you can prepend the list with more ways of naming a file uniquely. Serial numbering should be a last resort. You could also have an option in each podcast to specify how to name it 'Auto', 'HTTP filename', 'Incremental numbering', 'date'. And of course default it to Auto to give it sane functionality.