Also for amateur run and gun shooting the DSLRs like the d3100 / d5100 and canon 1100d / 550d / 600d aren't great due to the poor live view system. They just aren't built to focus whilst looking at the rear LCD, which means very slow focus times during video mode.
The Sony slt a33 / a35 / a55 however have the best focus speed during video of almost any camera and the quality of it is equal to that of the canon DSLR range, they just lack manual video control.
Don't get me wrong the nikons and canons give great video, it's just not perfect for people who like to press a button and get good footage, particularly whilst the camera is moving.