In a modern operating system like Ubuntu and Win7 every file has an ownership. A user cannot access another user's data. The only exception is the Admin in MS Windows or the root user in Linux.
Therefore if you want access from Ubuntu you can do the mounting as a super user in a terminal. I believe Ubuntu calls the first CD/DVD device /dev/sr0 so you can read/write it as root with commands
mount /dev/sr0 /mnt/my_dvdrom
Thereafter you can copy files same as any folder in the terminal.
For Win7 you can run Command Prompt as Admin and should be able to read/write the DVDrom drive.