I was trying to change the delete preferences on a podcast that was already registered, but I had lost network connection. It wouldn't let me save because it couldn't connect to the server (even tho I can't even edit the URL at this point because I was editing). If we can't edit the URL in edit mode, the program shouldn't complain about it being a bad url. At the very least, it should see if a network connection exists before complaining that it can't connect to the server.
That's a good point, when you're editing the podcast, there's no point validating the URL because it has already been validated. I'll add that to the future feature list.