I could not find a good QR Code Reader for my Kindle Fire. It does not have a back camera, so it was awkward lining up the camera - mirror image. And when I finally got it centered, it did not link to anything. I did install RedLaser onto the Excelsior iPad, and it worked. I also installed a QR at Golden Valley's iPad. I used it with a patron once who had printed a Real Estate home listing with a QR code on it for more information.
Adobe no longer supports Flash for Android, so videos may not be supported. However, Amazon installed a new "Experimental Streaming Viewer" in the Silk browser on the Kindle HDX, so we have been able to view YouTube videos. An alternative would be to install Dolphin browser (not the latest release), but since videos are working so far it may not be necessary.
To install non-Amazon apps may require "Side Loading." This requires turning on "Allow unsupported Apps" in settings. Be sure to turn it back off to protect the Kindle from corrupt Apps.
I have difficulty finding where things downloaded so I can install them. I even contacted Kindle Help four times and they were not able to find my Zinio app download (even with the "directions" from Zinio that were incomplete or incorrect.) I finally stumbled upon it and am now able to access my magazines. LoveMyFire.com has a demo to sideload ES File Explorer to access device's file system,
including "Downloads" folder.