Aside from the facility for You Tube videos to be embedded by URL, there is no other way of embedding multimedia content by URL that I can see, other than using it in preprepared HTML embed code.

So currently  I am using the editing tools with the following code

<embed src="http://www.bbc.co.uk/learningzone/clips/3208.bb.wmv" autostart="false"></embed>

replacing the URL address as appropriate.

It works fine and gets around the problem but is fiddly.  Many schools in England block YouTube.  There are other sites such as the BBC Schools site that provide excellent vidoe clips, but only provide the embed URL and not HTML code

What about opening up the opportunity to embed multimedia resources by URL?