From Juan Carlos Bagnell's note:
Ready? FIGHT! These two phones offer the most premier video recording experience on the market today. The Lumia 920 has been out for a little while, and the HTC One is the new kid on the block, but both feature an array of bleeding edge optics. Can HTC's UltraPixels unseat Nokia's PureView technology to crown the One as the smartphone video champion? Watch on my friends. Watch on.
(You may wish to skip over the opening two minutes, which includes a somewhat tedious parody of other comparison videos!)
As usual, maximise the window and up the quality if your bandwidth can stand it:
His conclusions are quite fair, I think, with the HTC One's larger lens and larger pixels producing lighter video images on the whole, but with the 2-axis lens-only OIS producing results that are significantly less smooth than the Nokia Lumia 920, with its 3-axis whole camera OIS implementation. I also found the Lumia's detail and colour handling to be superior, thanks in no small part to the high quality Carl Zeiss optics.
(via)