My Canon 5D mark 2 is not giving fine result when the video is played on TV. Why?

You may be loosing quality because the speed of your SDHC card is not up to the standard of your camera, the 5D records a very high quality image at a high MB/s you would need a SDHC card that can record at a faster speed than the camera so that there is no loss in quality, what memory card are you currently using?