Index: _source/plugins/image/dialogs/image.js
===================================================================
--- _source/plugins/image/dialogs/image.js	(revision 4463)
+++ _source/plugins/image/dialogs/image.js	Fri Dec 11 01:18:34 CST 2009
@@ -145,6 +145,8 @@
 
 	var imageDialog = function( editor, dialogType )
 	{
+		var absoluteURLRegex = /^[\/\\]|:/;;
+
 		var onImgLoadEvent = function()
 		{
 			// Image is ready.
@@ -422,6 +424,11 @@
 													original.on( 'error', onImgLoadErrorEvent, dialog );
 													original.on( 'abort', onImgLoadErrorEvent, dialog );
 													original.setAttribute( 'src', newUrl );
+
+													// Prepend base href for non-absolute url.
+													if( !absoluteURLRegex.test( newUrl ) )
+														newUrl = editor.config.baseHref + '/' + newUrl;
+
 													dialog.preview.setAttribute( 'src', newUrl );
 
 													updatePreview( dialog );
Index: _source/plugins/flash/dialogs/flash.js
===================================================================
--- _source/plugins/flash/dialogs/flash.js	(revision 4581)
+++ _source/plugins/flash/dialogs/flash.js	Fri Dec 11 01:18:34 CST 2009
@@ -177,6 +177,8 @@
 			'<div id="FlashPreviewLoader" style="display:none"><div class="loading">&nbsp;</div></div>' +
 			'<div id="FlashPreviewBox"></div></div>';
 
+		var absoluteURLRegex = /^[\/\\]|:/;
+
 		return {
 			title : editor.lang.flash.title,
 			minWidth : 420,
@@ -315,10 +317,13 @@
 											setup : loadValue,
 											commit : commitValue,
 											onLoad : function()
-											{
 												var dialog = this.getDialog(),
 												updatePreview = function( src ){
 
+													// Prepend base href for non-absolute url.
+													if( !absoluteURLRegex.test( src ) )
+														src = editor.config.baseHref + '/' + src;
+
 													dialog.preview.setHtml( '<embed height="100%" width="100%" src="'
 														+ CKEDITOR.tools.htmlEncode( src )
 														+ '" type="application/x-shockwave-flash"></embed>' );