Doesn't work for me Eric.
I had a working copy of 3.0.0. I removed this cleanly from the admin dashboard. I uploaded the latest 3.1.1 release via FTP and activated the plugin.
The pages have already got the shortcodes in from the previous version so a new version should display videos as soon as it's active.
I don't get the error mentioned above. What happens is that the plugin says it's active in the admin area but there's no menu item for it in the Settings menu and the pages don't display any videos, just the shortcode text.
I have tried deactivating all other plugins, deactivating Tubepress and reactiving it so it's the only active plugin but there's no change.
It's the latest copy of WP using the latest copy of a Studiopress Genesis theme.