#3 Not working in V4 CKEditor

[Anonymous]

Installed CKEditor V4 with KCFinder
When I click on the YouTube icon the web page dims and I get an error in Fire Fox.

NS_ERROR_INVALID_POINTER: Component returned failure code: 0x80004003 (NS_ERROR_INVALID_POINTER) [nsIDOMHTMLDivElement.appendChild]

I don't have a clue how to fix this.
Please help,
Robert Campbell