CD and MP4

I just built a new website and have a MP4 Video playing on the top page.
I spent all morning trying to get it to play, it shows player blacked out and speaker crossed off.
I went on my wifes PC to show her where I was and it plays.
Works in IE - Chrome _ tbird… But not CD.
I have shut off all extensions…

MP4, and its codecs, is not supported by Dragon.

See also

On a side note. Would using the VLC or other plugin be a solution?