Comment 8 for bug 347045

I finally found what causes the "Could not open location; you might not have permission to open the file" when auto playing a DVD. In XFCE, go to the Removable Drives and Media setting (Applications, Settings) and then on the multimedia tab, change the default command for Video CDs/DVDs from "totem dvd:/" to "totem dvd://"

The last slash is missing for some reason. Once I added the second / to the command, totem worked flawlessly when auto playing a DVD. I am using totem with the gstreamer backend and not xine.

I realize that this has absolutely nothing to do with totem, but it is still present in Xubuntu 9.10, and this bug report was high on the google search results.