I do not have a solution to your problem. I am curious about the situation though. Is there a reason your organization wants this to be easy-to-steal-and-expensive tablets? Especially when there's the security policy. And you'll have to keep them charged too. Why not just a cheap laptop. Or a pamphlet and TV? I realize it's difficult to get people to stop smoking, but fancy technology isn't always the solution.
I am curious about this too. I also work in IT and with several hospitals as customers. The IT staff in the hospitals I work with, small, medium, and large, all talk about things walking away from rooms, lobbies, etc. Surely there is a better solution, possibly more cost effective too... Besides, you will need to be able to recharge it anyway, so why not look for something that can be put on a table with a long core for recharge? If you can do that, then you could possibly look at touch screen media displays that access a media server hosting your videos. Viewer users use would then just be a touch screen display for the content (probably a lot cheaper, depending on media server and cabling install cost). This also keeps it off of the wifi... which from what I see in hospitals around here, the customer access devices on internal WiFi, the better...
Vax Vobiscum