To: epreston11
First make sure you are using the latest version of the program (4.2.1.166).
The non-activated version has no feature limitations, so let's try to sort this problem out. Please import only one of your HD files into the program, add it onto the timeline and save (convert) the file. Is the output video choppy? If yes, we'd need the original MPEG file for testing. Please write back and I'll send you the upload instruction on the support page.
BTW, does it get choppy no matter to which format you convert this file?
Hope to hear from you soon