File:Firejailed firefox playing video.png

Summary
Screenshot showing Firefox 52.4.0 running inside an X11 sandbox (Xephyr + firejail, with Openbox window manager). The Xephyr window is at its default size. Within the Xephyr display, one Firefox window is open, and shows a running YouTube video, to illustrate that playback works OK even within the sandbox. The main ("parent") desktop is running GNOME 3.22.2. Uploaded for use in a forthcoming mini-guide on X11 sandboxing (an addendum to Sakaki's EFI Install Guide).