Do you have .mkv files that play the video but there is no audio? I’ve gotten a few emails from my readers related to this subject recently. The solution can be pretty simple.
As long as you have the correct filter setup, all of your audio will play fine in a DivX Player/Web Player. This type of files require a filter called AC3Filter 1.63b Full. Make sure you download the full version and install it. After this you should be able to play your videos in Window Media Player or any other player.