want to burn AVI files from my camera Mem Card to a DVD?

You need a software converter to convert the movie from AVI format to DVD.
One of the best programs availbale for this is DVD Creator for Mac.
DVD Creator for Mac is a powerful Mac DVD burner designed for Mac OS users to edit and burn their videos files to DVDs. This Mac DVD creator can burn HD Video ( Burn MKV to DVD for Mac ). It supports almost all popular video formats including AVI, MOV, FLV, MPG, MP4, M4V, MPEG, DAT, VOB, 3GP, 3G2 and even HD videos such as TS, TP and TRP.
This Mac DVD Creator is complete with highly customizable DVD menus. It also provides you with flexible functions to edit your videos such as cropping video, trimming video length, and setting video effects etc.
Check here for information and download.