Hi,

This scenario is quite specific.
I suppose you are using Media libraries to store media files.
The Media Gallery webpart from that module could be suitable for this aim, however some additional page(s) for displaying the content in graybox will be needed to get a good result.

We would recommend to check appropriate Examples in our sample Corporate site to find how the Media gallery is used.

You can use the default transformation (the first one in the Media Gallery webpart properties) for the list and Selected item transformation for the full details view.

The play video link will have to lead to some special page, let's say /play.aspx, that will get the query parameter - e.g. media file FileID (rendered within the link by the transformation) and load an iframe with the video object into the graybox.

We would recommend using FancyBox - fancybox.net, as it is quite well made for this purpose.

Let us please know if you need any further details.

Regards,
Zdenek