Hey Kevin,
this looks like some pretty nice work!!! Now finding some time to install ffmpeg and test it...
Question about the node-red-contrib-ui-mp4frag. Is that a replacement of my node-red-contrib-ui-mp4-player or did you fork it to merge it afterwards? Because in our other discussion - where I presented my player node - I thought that we would build 1 player UI node that can support in the future all kind of video sources (mp4, mjpeg, snapshots via web push) to support all kind of users. We also have lot of less technical skilled users that won't be using non-mp4 sources, and we should give those users also the possibility to view their cameras in their dashboard.
And to support multiple player nodes is (imho) quite (free) time consuming, especially if we add e.g. an SVG overlay layer and other camera viewing features. And it would be a pity if one of the players offered those ui features, while the other ui node would not have the same features ...
So I still hope you are welcoming the idea to build one single UI node for camera viewing ...
