This is weird.
I have been trying to embed a video reliably across all browsers (that's not the weird part). I have it in mp4, ogg and flv formats. Well I couldn't get it to work with some versions of IE, surprise, surprise. So I tried to import the video into a fla and make a swf.
The swf did not show up embeded int the page. If I play the swf locally (not embedded) it works fine. So I went back to the fla and took the video out, including removing it from the library. I republished this mostly empty swf and tried again. Nothing shows up.
I am wondering if the swf file becomes corrupted with some metadata that a proxy or firewall does not like.