This use case seems already implementable with existing web APIs:
MSE rendering for static content and WebRTC rendering for live content
replaceTrack + canvas-based rendering for static content
Each one of these use cases have different benefits.
It would be good to evaluate what the expected benefits are of this technical solution compared to already available solutions.
Also the list of requirements are written with a technical solution in mind which does not help identifying the current shortcomings.
This use case seems already implementable with existing web APIs:
Also the list of requirements are written with a technical solution in mind which does not help identifying the current shortcomings.