User Activity

I transferred a few video clips from the camera to the PC. Two of them seemed to transfer ok but would not play on the PC? The file size is showing as 0kb on the PC. Is the file size too large?? Its around 1gb.
Is there any difference shooting movies in say AV or TV mode rather than in the movie mode? If shooting movies in AV will it be able to use the AV settings for example like 1.4x extender in preference to the digital zoom?