Just picked one of these up today.
It seems to work as advertised, so far.
I have not tried steaming wirelessly with multiple devices yet but I'm hoping this will be just what I wanted for long plane flights. I always end up filling my iPad storage with movies and TV Shows, then when I need to download something I am out of space.
A Seagate Wireless Plus 1TB WiFi HDD.
It has a built-in battery to last 9-10 hours and creates its own WiFi network. You join that network and then you can play videos, music, etc streamed from the HDD. Supposedly multiple devices can stream at the same time.
I have something similar, but it's not an all in one like that one. Really handy little device