Re: MediaStreamTrack disabling - effect on downstream MediaStreams?

> At a later stage, we could introduce a media processing object,
> which takes a MediaStream as its input and produces a new
> MediaStream as its output. In this case it's the actual media
> contents in the output MediaStream that is dependent on the
> input source(s).

This is what the MediaStream Processing API proposes to do:
https://hg.mozilla.org/users/rocallahan_mozilla.com/specs/raw-file/tip/StreamProcessing/StreamProcessing.html

I think (and discussed with roc and he agrees) that the proposed API to 
construct a new MediaStream from the tracks of existing MediaStream 
objects is okay.