导致普通iframe无法在php页面上显示的东西?

<div class="grid-5-12">
<iframe width="200" height="120" src="http://www.saweb.info/videos/nightclub.mp4" frameborder="0"></iframe>
</div>

I copied above direct from an "admin page" from Firefox developer page source and it works as standalone, but on the admin page itself it doesn't appear (it always did)

It also doesn't show even without the div. (It's in a parsley form and the iframe show the "current selected video")

Tested in Chrome and it also doesn't display while I can't find any similar error on the internet.

Anyone perhaps has an idea why the iframe don't appear / disappeared please?

is not used for play videos but to display another page. Some browsers might support this way of importing a video. But correct way to use tag like this for your video link.

<video width="200" height="120" controls>
  <source src="http://www.saweb.info/videos/nightclub.mp4" type="video/mp4">
</video>