Saving video to iMac

[Zip106]

I'm about to make a DVD (in iMovie) from video I captured at a friends wedding.
This was at the time the Icelandic volcano erupted and I want to include some footage of this at the beginning of the DVD as it was touch and go wether we'd make it (wedding was in Greece).

Is there any way of saving video from Youtube or BBC website to my computer that I'd be able to use?

Thanks.

[Blue Meanie]

In firefox you can get add ons such as easydownloader, etc, that will take online video, and save it to your computer. Just browse the add on side of firefox, and jobs a good un. Alternatively, Miro will download online content for you.