I saw your other thread earlier. I didn't have time to make a response about your embed tag. Your using an old html object/embed code for Quicktime. That can be the reason some people can't view you video. Mainly window users.
I took both your poster video and main video and put them into a html that has the new code to be used.
http://www.setfreedenver.org/trashh/
Take a look at the source code and you will see the difference. Also this code uses javascript so people with windows computers can view the video.
I use this program to generate the html for Quicktime. It free! And does a great job in making the html code. PAGEot.
http://www.qtbridge.com/pageot/pageot.html
Copy and paste the object/embed tag from the html that PAGEot makes and put that into your html page. Make sure the javascript page travels with the html. Don't forget to copy the javascript tag line from the head.
Using PAGEot: The poster frame goes under the general tab and the main main is set under the advance tab. You have any question ring back.
If the above doesn't fix the problem, it will fix it for window users. Also, to view your video. The viewer need Quicktime 7 installed onto their computer.