Web site hosted video won't play in Safari on MAC.

Question

I have a web application that runs in a web browser. One of its features is the ability to embed a video clip in a web page hosted on this application.
If I create a web page using the HTML5 <video> tag and an H.264 encoded MP4 file video clip, I can browse to this page from my web server and see the video. However, if I launch this same HTML page within my application (window.open(URL, _blank, ...)) it displays the page but refuses to play the video. This happens in Safari 5.1 on my Mac OS10.7 and on all browser tested on my iPad2 (Safari, Mecury, and Dolphin). However, the same HTML code plays fine through my application on all browsers on Windows (including Safari for Windows) and all other browsers (Firefox, Chrome, and Opera) on the Mac. It also plays through the default Android browser and the Opera Mobile browser on my Android tablet.
Here is a sample of the HTML that I am using to play this video...
<video height="713" width="950" autoplay="autoplay" controls="controls" poster="WhiteScreen.png">
     <source src="tradeintradeup.mp4" type="video/mp4" />
     <source src="tradeintradeup.webm" type="video/webm" />
     <source src="tradeintradeup.ogg" type="video/ogg" />
     <div id-noupdate>
          <p>Video format not supported by this browser</p>
     </div>
</video>
When the video does not play, I do NOT get the text in the div, I see an area where the video should be (so the browser is recognizing the <video> tag) but the video never loads or plays.
What am I missing?
Thank you for your assistance.
Dave Smith

Answer 1

Michael,
Thank you for your response.
I am aware of the autoplay restriction on iOS devices. What I see in my iPad(2) is an empty area of the window with no control to touch/click to start the video playing.
In Safari on my Mac, I do see the control bar with the rewind/replay and the play buttons; however, the word "Loading..." is displayed forever in the bar. Again, the browser recognizes the video tag and creates the control to play the clip, but the video never actually starts playing. It appears that it hangs trying to download/stream the content.
I have other pages that embed audio clips using the HTML5 <audio> tag. These play fine, as expected, with Safari on my Mac and on my iPad. Yes, I have to manually start the audio on the iPad, but it runs fine once started and autoplays on the Mac. Of course, these audio files are much smaller than the video files that will not play.
I have looked at the codec used for the video to see if it might not be compatible with the Mac Safari browser, but the video plays directly from my web site. It only fails to play when launched in a pop-up window by my web application. I realize that this points to a problem in my application. I am trying to get some ideas about where to look in my application for the problem.
Thanks again for your time and your input.
Dave Smith