Video on tablets, are phone cameras "good enough"

I read that people with tablets watch video quite a lot. And they watch all the way through much more compared to people looking at a computer screen.

I wonder what sort of cameras can produce a reasonable standard? I use a Kodak Zi8 which I think is the sort of standard a phone camera will produce for the next few years. It is ok for YouTube till blown up full screen, then maybe not. But a tablet screen is not that big usually. I think quite a range of cameras will be ok.