Biznews Hi. I've checked and You are already using Code Mirror, so the video and iframe can be added. And they are being added in AdAgency as well, but there is a different problem there that You cannot see it. Looks like the editor's css is being overwritten. Probably because it's not a standard one. Add this to /components/com_jce/editor/tiny_mce/plugins/source/css/editor.min.css
.source-editor-container {
width: 100% !important;
heigth: 100% !important;
}