A - In most cases, the reason you can hear the video but not see it is because you do not have the correct software or codecs installed on your computer. Try the following:
1) Download QuickTime for MP4 and MOV movie files.
2) Download VLC for MP4 and MOV movie files.
3) Download K-Lite Codec Pack for older PC playback compatibility.
4) Download Perian for Mac playback compatibility.