I added a topic in the "Producing Podcasts" discussions sections.
http://discussions.apple.com/thread.jspa?messageID=11226102#11226102
After advice from Roger Wilmut, I contacted iTunes support:
http://www.apple.com/support/itunes/ Then clicked on 'Other iTunes Store Features' in the list and then on 'Podcasts'."
This is the response i got back from iTunes support:
"Hello Richard,
Good Evening! Thanks so much for taking the time to contact me here at iTunes Store support. My name is Breanne and I will be more than happy to help you out today.
I understand that you are concerned that the previews for video podcasts are played in 4:3 format and when you download them they show in 16:9 format.
I am sorry for any inconvenience this has caused. Please be assured that we are always looking for ways to improve your experience with the iTunes Store which is why we have a form you can fill out to submit your ideas and opinions.
We are always willing to learn more about what our valued customers, such as yourself, would like to see from us:
http://www.apple.com/feedback/itunesapp.html
We here at iTunes recognize that no one is better qualified to provide feedback about our Store than the members of our iTunes Store family. Your email may make the difference.
Sincerely,
Breanne
iTunes Store Customer Support"
As you can see i didn't get an answer to the question, but i went to the feedback link and submitted my thoughts.
I am going to try to get more from the iTunes support.