When you're looking at your library on Screencast.com, are you logged in to the website? The default folder that Camtasia uploads to is set to the 'Hidden' privacy by default, which means the links work fine but it doesn't allow users to view the entire folder in your library. New folders created through Camtasia or via the website are also 'Hidden' by default.
If you log in to Screencast.com you will be able to see all of your folders, including the hidden ones. Let me know if this doesn't resolve your issue.