Total geekpost warning. Suppose that you’re using Ubuntu and you want to copy a DVD. There are of course several ways to do it, but if you’re not opposed to command line wrangling, just open a terminal and issue the following commands:
sudo umount /dev/dvdrw1
readom dev=/dev/dvdrw1 f=/path/to/file.iso
Where /dev/dvdrw1 is the path to your dvd-drive. Burning the ISO-image is as easy as a right click on the file and selecting ‘Write to disc…’