Putting images onto an SD 630

I'd like to transfer some AVIs and photos from my computer back onto my Powershot SD 630 to be able to view them on its great screen.

I thought that when I connected my Mac to the camera via USB it'd show up on my desktop and I could drag n drop at will. Not so.

Is there any way of doing this in OS X?

THANKS

No - you need a card reader to do that, and the SD630 won't play them back unless they're in Canon-stock (unedited) format in the right Canon camera directories.