There is a lot of info on the internet about video. Overwhelmingly so.

I believe the Mac will read the Canon DV file but, I think maybe don't know, if Sony is a little different and may not be usable with Mac. I use a Canon miniDV and a Casio SD (which wraps the file in an AVI container which takes a little more fiddle like QT Pro, special video components in the QT library). Both give me good service with Mac.

I'm pretty sure the Canon will firewire import into the Mac without a problem. I'd double check on the Sony were I you.

You have to decide how you are going to use video and what size image you want before you start so look into that. The larger the image you want, the more pixels you have to pack onto tape/flash, the larger the file will be. Different formats use different compression standards to shrink the file size and that is the problem.

iMovie 08 supports standard and high definition video, as well as the most popular formats, including DV, HDV, MPEG-2, MPEG-4 and even AVCHD.

Google around for info on MPEG.

MPEG-1 is older compression which contains the popular MP3 audio format

MPEG-2 is broadcast quality television and what you find in DVD VOB files.

MPEG-4 is newer compression used with support for DRM; one form is H.264 for iPod.