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This post has been migrated, original date 11 Nov 2009 The embed HTML element is not a valid XHTML element, this creates a problem when you want to insert objects into your Rich Text fields such as You Tube videos. To validate XHTML sitecore uses the file /sitecore/shell/schemas/sitecore xhtml.xsd. By editing this file we can allow usage of the embed element. Beneath the /xs:schema node add a definition for the embed element:
 <xs:element name="embed">
    <xs:complexType mixed="true">
      <!-- from -->
      <xs:attribute name="align" type="xs:string" />
      <xs:attribute name="alt" type="xs:string" />
      <xs:attribute name="class" type="xs:string" />
      <xs:attribute name="code" type="xs:string" />
      <xs:attribute name="codebase" type="xs:string" />
      <xs:attribute name="height" type="xs:string" />
      <xs:attribute name="hspace" type="xs:string" />
      <xs:attribute name="id" type="xs:string" />
      <xs:attribute name="language" type="xs:string" />
      <xs:attribute name="name" type="xs:string" />
      <xs:attribute name="src" type="xs:string" />
      <xs:attribute name="style" type="xs:string" />
      <xs:attribute name="title" type="xs:string" />
      <xs:attribute name="unselectable" type="xs:string" />
      <xs:attribute name="vspace" type="xs:string" />
      <xs:attribute name="width" type="xs:string" /
      <!-- used by you tube -->
      <xs:attribute name="type" type="xs:string" />
      <xs:attribute name="allowscriptaccess" type="xs:string" />
      <xs:attribute name="allowfullscreen" type="xs:string" />
This definition was created based on the attributes list at and some attributes used by You Tube. You may need to define additional attributes as needed. Next we need to add a reference to the new embed definition in the object definition. Find the definition and replace the first part with the following which has the embed reference:
  <xs:element name="object">
    <xs:complexType mixed="true">
      <xs:choice minOccurs="0" maxOccurs="unbounded">
        <xs:element ref="embed" />
        <xs:element ref="param" />
        <xs:group ref="block" />
        <xs:element ref="form" />
        <xs:group ref="inline" />
        <xs:group ref="misc" />
Save the file and your embed element problems should disappear. Remember however that doing this will mean that your site is no longer XHTML strict.