Fullscreen works for me on your site on IE7 and FF2 (MBTV Demo).
This code actually works…
[flash https://camtasia.mdsmarkets.com.s3.amazonaws.com/Introtest.flv w=600 h=500 preview=force mode=3 preview={https://media.mdsmarkets.com.s3.amazonaws.com/Images/MB_410x380.jpg|410|380} f={image=https://media.mdsmarkets.com.s3.amazonaws.com/Images/MB_410x380.jpg&logo=https://media.mdsmarkets.com.s3.amazonaws.com/Images/MB_410x380.jpg&overstretch=true&usefullscreen=true}]
…but it doesn’t because WordPress changes ‘x’ to the HTML code of the multiplication character ‘x’ instead of leaving the alphabetic one – this is because of the digits before and after it.
I suggest to rename the images’ filenames and wait for a plugin update. Last one could take some days/a week as of I concentrate on the media manager at the moment.
p.s.: I should change some paragraphs in the readme file regarding some new features :).