When the TV signal is processed to compress its size for transmission the video component takes more time to process than the audio and there is always a slight, barely noticeable, lag between the two. There is also more delay intoduced in the receiver when it processes the complete signal back into separate video and audio.
The brain normally compensates but this can be seen if the camera position is behind the head of someone who is talking. It then becomes more obvious. You can see this quite a lot on the morning breakfast programmes.
If you've got a fancy TV set with lots of image enhancement then this also takes time and the lag between the two becomes too much. The TV will then have an audio output, as Rolf says, which will take into account the extra sound delay. Using this will be the best you can hope for unless you have a very expensive AV amplifier. These often have an adjustment for audio delay. |