I have a DVD+R DL disk that i want to make a copy of using my Mac. It's got about 7gigs of content, but i'm wondering if i can burn it to a standard DVD. I don't mind if the rez suffers a bit, i'm just not sure how to do it.
You can't do this, simply put. The video on the disc is already muxed, so you can't just downrez it to fit on a DVD-5.
What you could do (I think), is use a program like DVDxDV to strip the video off the DVD into a Quicktime format, and then use your NLE or a compressor to recompress the video so that it will fit on a DVD-5.