Most of the videos play well in templates (I used that here), I think that is not an issue.
Playing videos or live inputs in another Caspar layer won’t let you change the video parameters in sync with HTML templates (you can send the commands to both but dealing with that in the client side (both in the official as well as custom ones) is inefficient.
I suggested VLC because it gives you more versatile live input options (even TV tuners) but you can show any WDM input that way. NDI Virtual Input is very convenient for that matter.
That’s very cool!