Thank you for the Screencast!!
Unfortunately the error message is not helping me to debug this. Furthermore I could not reproduce the error in may test blogs. That is why I think that it might be an unwanted interference with one of your other plugins.
It would be great if you could find out which other plugin might be involved too. Deactivate one other plugin, check whether the error occurs and activate the other plugin afterwards again. Once I know which other plugin is involved, I might be able to analyse the plugins and resolve the problem.
The "URL of the media files directory" value (on the general settings page of podPress) should be a complete URL. Click on the question mark to see a suggestion for the value.