Quote - The web site I post to when playing the animation it jerks even worse and doesn't play as smooth.  Does this have anything to do with the compression/codec?

Could be... if you're sending the video to a host site (like YouTube or Vimeo) they are compressing what you send them, as well as probably converting it (usually to flash video, FLV instead of AVI or MOV). If you compressed the video first, and they re-compressed it, it's going to look worse than it did on your computer.

Most hosting sites have recommendations for how to prepare your video before you send it for best results. Look for a FAQ page at the hosting site, and you'll probably get some useful tips both in general and for that video host in particular.