Well that video is not completely smooth it appears to pulse whenever the motion speed increases. I know this might be obvious to many reading but the speed of the motion in the game also effects the feeling of smoothness, this is why fps is very important in racing and fps games but less so in turn based strategy games with slower movements.
For example in a racing game:
a) if I cam traveling at walking pace the amount the difference between frames is very slight (lets say under 10cm in game measurements per frame at 14fps) as I am moving slower. This in turn helps make the animation appear smoother as the difference between frames is smaller making everything seem smoother.
b) If I do the same test at 200mph the difference between the frames is now in the region of meters not centimetres per frame. This means the difference between the frames is much larger making the frame rate seem more choppy than before.
You can see this effect in the video you link to, in parts it seems more choppy than others and this happens when you have faster movement (bigger difference between frames) on screen. However this effect is hard to tell for sure as the video is not running at 14fps but much standard 30fps and the encoder is mashing it together giving you not quite the same experience as if you saw it running at 14fps as it will blend the frames a little.
Another example is how a game appears to get slower when turning around at speed in an fps, usually the frame rate has not altered at all just the difference between each frame in the game world is a lot bigger making the game feel slower and less responsive compared to turning round slowly.
This test above is pretty easy to reproduce, you could even do the test using two flicker books with both small and large motion and testing them. Your eyes and brain will make the slower motion one look smoother compared to the large motion one even though the fps is the same on both.
Edwin