Thanks everybody for your suggestions. My Mac is an OX S 10.
there doesn't seem to be aDVD icon for me to drag it to.
It is not a home movie - recorded from TV.
In Disk utility it told me I could copy home movies that had been made on my computer - I tried it but the DVD, though it looked burned, seemed to have nothing on it . .
What model is your Mac - not operating system. And does it have a super drive or a combo drive. You need a super drive to burn dvd's. But you can burn cd's with the combo drive.
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Latest addition 2010 Mac Mini server
I found out that the DVD I was trying to copy didn't actually have anything on it - although it was burned and you could see that. So I haven't tried it again but feel sure that what you said is what I did in the first place and that it will definitely work!