Adobe has made it clear that it will not be officially making the flash plugin compatible with the newest Android version v4.1 (also known as Jelly Bean). Default web browser in the Nexus 7 is Chrome, which unlike its desktop version does not have built in flash support.
It is funny that Adobe, infact warned that even force installing flash on Android 4.1 devices would not work, but fortunately, xda community did an admirable job in making it fully compatible. If your device did not come pre-loaded with Jelly Bean OS, the stock web browser still exits and you will easily be able to sideload the APK of Flash and then enable it inside web browser. Download the flash player from link given below and install it on your device.
Problem and Solution with no stock browser – Devices like Nexus 7 do not come with AOSP (stock) browser. They will need to root Nexus 7 and then install the APK for the stock web browser. Read our tutorial on how to install stock web browser in Android 4.1, aka Jelly Bean.