I'm not real sure what you mean....Is your problem that you cant preview your downloads if so it would mean you need codecs...
If you are using XP, this pac is the best...
Download XP Codec Pack 2.0.7.1 - XP Codec Pack is one of the most complete codec pack
If you want a player with the codecs pre-installed VLC is the best and it's free....
VLC media player - Overview