Windows 8 tablets are convenient for watching videos that are streamed from the Web. Sometimes, though, when you are finished watching a full-screen Flash-based video, there is no way to get out of it unless you have a physical keyboard attached (usually via Bluetooth) and can hit the Escape key.
In these instances, your only option might be to kill the Adobe Flash process. To do so, swipe in from the right side of the tablet, tap on the Search Charm, and tap in the text box to bring up the on-screen keyboard. Simply type Task Manager and hit Enter.
This will bring up the Task Manager, through which you will be able to see all the running applications on your tablet. Tap on the Adobe Flash Player entry to select it, and the tap on End task.
This method will take you out of the Flash player's full-screen mode, but it will crash the Flash plug-in in the process. It should only be used when you can't find any other way to exit a full-screen Flash video that you are watching.