[nrivadeneira]

I'm sure there are Windows and Mac equivalents, but Ubuntu has a timed screenshot option. It would be fairly easy to just set the timer, go the the website, and wait. But I agree, most people probably won't care enough or think of it.

[sirsar]

Even if there isn't one currently, windows exposes an interface to the screen through gdi+ which can be used in a C++ program, for example.

[mmvvaa]

With quicktime player, one can just create a new screen recording, and wait.