Yes, it does scroll slowly and I really have no idea why. Mine seems fine when I want to scroll downwards but scrolling upwards, it's very sluggish and very slow, exactly like how you show in the video. Also, the Lumia 620 in Malaysia at least, has this sort issue where the screen cannot register multi touch correctly. Happened with mine, but only for a couple of times a week. Been a long time since it last happened and it happened again just a couple of hours ago but only for a couple of minutes. Now it seems to be fine though...
Now I'm not sure whether this is a hardware issue or a software issue. I did switch off the screen magnifier thing though...