formatEmbeddedContent() {

		let _appendParamToIframeSource = ( sourceAttribute, sourceURL, param ) => {
			queryAll( this.Reveal.getSlidesElement(), 'iframe['+ sourceAttribute +'*="'+ sourceURL +'"]' ).forEach( el => {
				let src = el.getAttribute( sourceAttribute );
				if( src && src.indexOf( param ) === -1 ) {
					el.setAttribute( sourceAttribute, src + ( !/\?/.test( src ) ? '?' : '&' ) + param );
				}
			});
		};

		// YouTube frames must include "?enablejsapi=1"
		_appendParamToIframeSource( 'src', 'youtube.com/embed/', 'enablejsapi=1' );
		_appendParamToIframeSource( 'data-src', 'youtube.com/embed/', 'enablejsapi=1' );

		// Vimeo frames must include "?api=1"
		_appendParamToIframeSource( 'src', 'player.vimeo.com/', 'api=1' );
		_appendParamToIframeSource( 'data-src', 'player.vimeo.com/', 'api=1' );

	}
Enforces origin-specific format rules for embedded media.