avi files are usually video -- though there so many differing video codecs it's hard to guide you.
Your post is unclear -- did you get stuck downloading the file from somewhere on the internet or did the interruption occur when you were burning.
Normally you'd download stuff to the hard drive before attempting to burn.
For audio you'd use Toast or iTunes as the burning program -- for video the picture is more complicated and as (thankfully) I don't have a Mac......
thank you fihart,I know the problem.
First I have to convert avi to DVD format(divx vob...), then I used itune to burn it to DVD, now it is already done.
I did not get stuck when downloading, it is because I did not use the converter rightly.
Anyway,I am very happy it is ok now.
Thank you again.