just to clear this up, I know alot of people misunderstand what the
torrent file is. A torrent file is not the actual file that you download and watch. The torrent file is just a very small file which gives directions to your BT Client.
With that said...The reason why you may not always have sound and/or video, is because your media player is missing a certain codec (the tool which codes & compresses data). I would suggest downloading a "codec pack", which will enable your media player to play the majority of files that you will ever play.
The
K-Lite Mega Codec Pack is a good codec pack to use.
Hope that helps
http://www.free-codecs.com/ is an excellent place to find any video/audio codecs & tools that you ever may need.