I've been using MyFeed for several months now. In the last week or so, iTunes started prompting me for my password over and over again, and no matter how many times I re-enter it it says the authorization failed.
I poked around at the site and discovered the way the URLs are built has changed, so I tried to set up from scratch just in case that was the issue, but even with the new URLs it keeps telling me authorization failed when I try to add the feed to iTunes.
I know the login is valid because I logged into the website with it to post this. And my account page says I have a paid-up premium membership.