Have you seen this?
So the solution is simply to configure TinyMCE to accept the iframe tag as a valid element. I'm using EPiServer CMS 5 with TinyMCEAdapter so I had to add:
to the tinyMCE.init event.
Thanks Steve and Frederik for the pointers.
I'm working on a site where editors occasionally need to insert iframes into a few xhtml page properties. As far as I can see there are 2 options here, the first is to create a dynamic content control that will do this automatically, the second is to disable the filtering mechanism so that iframe tags don't get stripped out.
Unfortunately we're using #mce_temp_url# which doesn't have support for dynamic content. So is it just TinyMCE that is filtering out iframe tags or do I need to dig further into EPiServer to enable them?
Any suggestions are very welcome!