As was mentioned, it's just the refresh rate. Film is projected at 24 frames per second and the higher refresh rate exceeds this effect and creates the 29.97 frames per second of video.

The other fact may be that films shot in HD video have a sharper look than film. Film has softer edges and less contrast, while things shot on HD video have a mirror-like clarity to them. So, combined with the refresh rate, it will not resemble the motion picture film you are used to seeing.

If you have your TV settings properly then HD releases shot on film and the film-like 24fps video cameras will look as they should. A lot of newer TVs have the default being the higher refresh. I don't know where this setting would helpful, maybe broadcast HD like sports that doesn't film at 24fps?