When you say it looks fine on the monitor, do you mean an NTSC monitor or your computer screen? If your animation contains sharp and contrasting lines, it’s very possible for it to jitter. Search the AfterEffects forum for some ways to reduce the jitter.
Also, it could be the way the animation was encoded into mpg. I always use Cleaner to do the encoding for DVDs because I’ve found that it does a much better job than the Encore internal encoder.