As you probably know, Jelly Bean is not supported by Adobe Flash. They will not be updating Flash to work on Jelly Bean, which is a real shame. Sure, Flash never worked too well (even on computers), but it was the fact that we had that option which made Android special in one more way. Luckily, all hope is not lost.
Getting Flash working on devices like the Galaxy Nexus and Nexus S (which still have stock browser) is as easy as sideloading the Flash APK (which you can get here). There you go, you have Flash! Now just enable plugins in Browser settings and you’re good to go.
If your device doesn’t have stock browser, like the Nexus 7, you can’t use Flash. Chrome doesn’t support plugins. So what will you do? Well, sideload the browser! Unfortunately, this procedure requires root, so I’ll have to dish out the standard disclaimer. Do this at your risk, and no one but you is responsible for any possible damages. Be safe and have fun. Use protection.
You’ll need to download the stock browser from here (it comes from the Nexus S JB ROM). Now use a root file explorer like ES File Explorer or Solid Explorer to put it into /system/app. Then change permissions to rw-r–r– or 644 or however you like to signify it. If you see browser provider.apk and browser provider.odex, you’ll need to rename them and add a .bak to the end (just to get rid of them without deleting them). Reboot and you’re done!
If you don’t want to root, you can always sideload Firefox browser and it works well with Flash. You have options! So those are the ways to get Flash working. If you want the original instructions or to join the discussion, hit the source link. And enjoy Flash on your Jelly Bean device!