I understand mp4 playback won’t work in the HTML producer because of the underlying missing support in CEF. However there are builds of CEF that include the mp4 container format (Nik build from memory). Is there a particular reason Caspar isn’t using a build supporting mp4, or is it possible to add this support?
Thanks
Going a little bit sideways on the answer, but couldn’t you achieve the same outcome by playing your html template on top of a casparcg video layer?
Yes but!!! You loose the ability to manipulate the video to the extent that the template can. The idea is in HTML templates, you can break video into sections and edit them independently like this example or this one. And it gets even better with video and Canvas!
Some HTML sources I want to utilise have embedded video and therefore I unfortunately can’t manipulate the video into different layers. One example is social media. VP8 isn’t as common as google would like it to be 
I think the main reason for not supporting mp4 is that is how the default builds of CEF are configured. If we want to enable that then that will require one of the maintainers to build it every time we want a new version.
It is a fairly simple task if all goes well, but it takes quite a while.
That said, I am hoping this can be done for 2.3
Good to hear. Would love to see this implemented.