Aren't you asked to turn electronic devices off when you enter a hospital? I don't understand why there's an exception for the iPad. And at least from what you can see in the video their iPads are not in airplane mode, but are actually connected to WiFi and the AT&T network.
When cell phones were new, there was some hand-waving regarding the risks of planes crashing, respirators stopping, etc. As is often the case, these risks were not very credible.
The signs stay up because while the RF signals won't kill anyone, listening to people jabbering on the phone is very annoying. For example, my wife's pregnant, and we spent some quality time in her OB/Gyn's waiting room the other day. Hearing another patient screaming into phone with a graphic recounting of the bursting of some sort of cyst for 30 minutes made the experience of sitting in a 90 degree waiting room for a half hour that much more noxious.
I've been in waiting rooms, recovery rooms, at the bedside of post-surgery family, and never been told to shut off my iphone (despite written warnings saying exactly what you mentioned).
