@aworan I followed your tutorial and installed PepperFlash on a RPi3 running Ubuntu MATE 16.10 and Chromium 500.0.2661, which was installed as per instructions on this site.
It works but erratically, sound sometimes but no video. Raspbian PIXEL, however, has Flash installed in Chromium and works well. Is there any way to use Flash files from the PIXEL install to get Flash running in UB 16.10 Chromium?