Likewise I installed ffmpegx last year but had problems getting it working properly. It's supposed to be very good.

I used to working with full quality videos using dvd studio pro so I'm relatively new at the concept of burning highly compressed videos such as mpeg4, etc. that one gets from over the net. I've fitted up around 3 hrs max on a dvd so far using dvd sp. Not brave enough to fit more on.

Found this: http://www.roxio.com/dvd_forum/faq.jhtml