very good video. Once you open this up to other clients (browsers, Esri, QGIS, etc.), it will expand the reach exponentially. Having worked with numerous server products, I am especially impressed at how simple this is. Drop a .map linked to multiple other .maps on a server, and it is now available everywhere, fully symbolized. It is the easiest server implementation out there, and it is also likely the most flexible in terms of a single repository connected to Esri REST servers, Postgres servers, SQL Server, other images, etc. I love the fact that someone can simply create a link like you have for the REST cannister. Doing that kind of connectivity take a good deal of programming that most users don't have. In this case, a few drag and drops gives a novice the kind of server sophistication only available to high priced consultants.
I can't wait to see where this goes...