Download Adobe Flash Play 11.1 apk here or download it from XDA Developers. After the file has downloaded open and install it.
Please be sure that “Install from unkown sources” is checked off in the Android settings for the Nexus 7.
Install Firefox Beta browser from the Android Market.
That’s it, now you have Flash support on your Android 4.1 (JellyBean) Google Nexus 7 tablet! Couple things to note:
1. This will NOT work with the current build of Google Chrome. A dev may fix this in the future but Google nor Adobe will be adding Flash support to any future builds of Android. I’ve also tried: ICS+ Browser and Dolphin Browser HD, both of which don’t work with the method used above. FireFox seems to be the only browser currently that works with the flash plugin in Android 4.1.
2. that by default FireFox Beta has plugins set to on demand which can cause some minor inconviences, however you can remedy this by going to:
FireFox Beta settings (three dots to right corner) -> Settings -> Plugins -> Select: Enabled