It does seem like it would be nice to have natively! I read a blog post about someone using Blender to send OSC to SC by way of scoring video so there are others with the use case…
Ardour offloads video display to a second program, xjadeo, so if you’re going that way, better to use xjadeo directly (less weight).
Stupidest software name I’ve ever seen but it promises OSC-synced video display. I’ve used it through Ardour and it works cleanly.
It’s a matter of development priorities. Currently there are 131 open enhancements (not counting bugs!) so, unfortunately, the driving factor is not that people want it – the driving factor is, who will do it.
It seems that there’s no open or closed issue for a movie view – you could open a feature request. That’s how to communicate that you would like it as a a feature.