YouTube and Vimeo API scripts are loaded in the header, while the iframes include onload actions to initialise the APIs, and the anchor elements include onclick actions for setting status. This system includes none of the media titles or content detection of mediaboxAdvanced, and there are some limitations to this mostly-CSS approach, but in general it’s pretty usable. Check out the CodePen.io page for more details and the source code.
You can also check out a demo using next/previous buttons to navigate through groups of overlays. This would require a bit more development to make it useful (especially developing the CMS integration to make it automatic), but is a starting point for further investigation.