I don't have a cover (yet) for my Kindle, and while I do have concerns about the glass screen, I think it's pretty usable without much or any protection.
That back pocket thing though...I've never understood that. We've got commercials where folks put smartphones with big glass screens into their back pocket too, sometimes leaving half the phone exposed. Do people actually do that? I practically never sit down, and I can't imagine putting a glass-screened device in my back pocket.
Addendum: ...I hope the kid in the second video has been resourceful in finding free ebooks on his own. Otherwise, with the grandmother's account (she was apparently not monitoring purchases on her account, and I doubt the kid has his own credit card [but it's America so who knows]), that kid could become a dangerous financial parasite.
