Well I have this video clip I downloaded, and when I try to play it, It say's Error Downloading Codec, And just plays the Sound, But not the Video. When I try adding it to Windows Video Maker, It says error Downloading codec cause its not ticked to automatically download codec. What does this mean, can I fix this problem
It means that you are missing a video decoder for whatever video stream it contains. Use MediaInfo or similar to check what it is, then download and install it.