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...
Real Users find the one combination of bizarre input values that shuts down the system for days.