I recently spent a couple days debugging an issue with our Flash application in Microsoft's Edge browser. Several developers were updated to the Anniversary update for Windows 10 and if you tried to load the page with our Flash application it wouldn't display and right clicking would show the "Movie not loaded" message. Everything worked fined in Chrome, IE and Firefox. I verified that Flash applications on the internet worked to eliminate that part of the problem.
Things go weird when I tried accessing the application from a different machine and it worked fine. Further testing showed that the application would load fine on port 80, but not port 8080. I was really narrowing it down and finally found that in the Anniversary update a new setting was added to the about:flags page called "Allow Adobe Flash Player localhost loopback". After turning this on and restarting the browser the application loaded fine.