What is the source of the video? I mean its web address. Can you access the video directly? I mean not using your web page. You said it was a YouTube clip. Some areas of the world censor their internet. And some web sites also block their content to some parts of the world.

I don't know what goes wrong in this case.
The Flash player doesn't seem to work or get displayed in the iframe, but work when opened in a new tab.

• http://www.youtube.com/embed/jsUjzNHlggM?rel=0

I can't right-click the player area as well, but the DOM Inspector finds the EMBED with the Flash player if I click the black space.
Firefox doesn't seem to like the CSS of the class .content-1 DIV container because it works if I move the iframe out of this container and paste it just before this DIV or elsewhere.

fredmcd-hotmail, nothing can be blocked here. It's just a YouTube cartoon on my own site, which is displayed normally in other brosers.

cor-el, so I can’t have iframe video inside the DIV container, can I? Is it nothing to be done with it, excluding moving video to another part of the page? I don’t want to move it :-(

First, get it to work. THEN worry about making it look good.

A good place to ask advice about web development is at the mozillaZine "Web Development/Standards Evangelism" forum.

• http://forums.mozillazine.org/viewforum.php?f=25

The helpers at that forum are more knowledgeable about web development issues.
You need to register at the mozillaZine forum site in order to post at that forum.

Who is the source of it: Firefox, Shockwave or Youtube?