Well at least I guess we agree that
possibly Android devices that are older than 4.2.1 might not work with the Rocketfish receiver per the OEM.
The "certification" link you have in your YouTube video is for "Wi-Fi CERTIFIED™" devices. This doesn't necessarily mean that they are "Wi-Fi CERTIFIED Miracast™" devices as well. Miracast actually doesn't even have a logo or indicator. Although the technology is shared between Miracast and WiFi Direct they are separate technologies. I've attached a PDF taken directly from the WiFi Miracast website covering this.
The link for Wi-Fi CERTIFIED Miracast™ devices is
http://www.wi-fi.org/wi-fi-certified-miracast™
I'll return the Rocketfish for now and perhaps wait until someone is able to confirm that the Z tablet is compatible with it then I'll go back and revisit it again.