Ok so if you're trying to burn a DVD you'll likely need to convert the file to something other than .iso. iso files are the compressed file that is actually burned onto the dvd in this case. Personally, i would import the video you need into iMovie (if it's long it could take a while so just do it at night) then have it burn the dvd. There really isn't a way to directly convert a video file to an info file like .iso.
If you don't feel like doing that, you can try converting the file into .mpeg or .mp4 and see if you have better luck burning either of those, but i doubt that will work. You're best bet is to use iMovie, I've used it before and it works really pretty well.
Enjoy college now, because when you graduate. . . it's called "alcoholism".