Version:           1.4.5 (using KDE 3.5.6, Gentoo)
Compiler:          Target: i686-pc-linux-gnu
OS:                Linux (i686) release 2.6.19-suspend2-r2

Reproduction:
1. Pick a podcast
2. Trigger Amarok to download episode
3. Interrupt the download (works for me with both cancel and download error)
4. The localurl is set to the _directory_ name where the episode would be normally downloaded.
5. Amarok shows the episode as not downloaded, but after almost any action associated with it changes it's mind and shows it as downloaded, even though it is not playable.
6. If user asks Amarok to delete the "bad" episode, Amarok removes whole podcast directory.

I first encountered it with a pretty large podcast (I had to redownload ~4G of data...). I've later reproduced it as described above with a small one. Just download episode or two, and abort download of the next one.

I took a quick look at sources, by best bet is that the problem is caused by PodcastEpisode::downloadMedia which sets:
m_localUrl = m_localDir;
The filename is later added in PodcastEpisode::downloadResult:
m_localUrl.addPath( m_filename );
but only if download was successful. It is not obvious for me how the dir-only version gets stored in DB though.

One more point: I believe it is also possible to delete whole podcast dir by trying to delete episode that is just beeing downloaded. Just: download episode 1, request download of episode 2. select another episode, select episode 2 (local url will show only directory part), rightclick -> delete downloaded podcast.

My best bet at fix would be to move the " m_localUrl = m_localDir;" to PodcastEpisode::downloadResult: when it was already verified that the podcast was correctly downloaded.