What happens in WordPress if you try to enter unfiltered HTML in the text view of the editor?
iFrame Embed Code
The embed shows up in the Visual editor, and then, after publishing the iFrame embed is stripped out and only the “safe” stuff remains. That is what should happen!
Frozen Romania from Stanly on Vimeo.
Inline CSS
If you try to enter inline CSS, what happens?
It is allowed. The styled text above (green and bold) sticks.