I've found that TinyMCE rejects the iframe tag when it is pasted into the HTML area by default. I tried fixing this by editing init.js in the \application\modules\editor\assets\js folder, adding "iframe[src|width|height|name|align]" to the "extended_valid_elements" keyword. I saved and uploaded the file, purged the cache of TangoCMS, but the iframe tag is still rejected. What else do I need to do? Using TangoCMS 2.6.1, with a heavily modified purity theme.
I got it working this time, by disabling the use of Google's CDN. Was that necessary or is it just a coincidence? I simply tried again exactly what I've written above, but now also turning off Google's service.
Hum, that shouldn't effect anything. When Google CDN is enabled the only file we get from Google CDN is jQuery, when disabled it uses a local copy of jQuery. Strange =)