On the page for the type http://schema.org/VideoObject
you can find the "Expected Type" for each property.
For url
and embedURL
it says: "URL".
If you want to provide a URL in HTML5, you have to use the href
attribute (on link
, a
, …), the src
attribute (img
, …), or any other ways that are defined.
If you use a URL as value of the content
attribute of a meta
element, it will represent a string (looking like a URL), not a URL.
You can find the relevant part in the Microdata spec, 5.4 Values.