Never had this problem before. I edit a Video in PD9, go to Produce and choose YouTube, select 1080x720 (My camera's max), fill in the appropriate blanks and push the button to upload. There are large pixels showing in the video on YouTube, but not if I view the copy on my computer. I have tried uploading with a higher definition, video encoder on and off, preview on and off, private and public. Any ideas out there as to what's going on or do you think its on YouTube's end?
Thanks