You normally get it when you watch porn or other pirated
videos
And it will prompt you to download a codec in order to watch the
video (active x)
once you download it. TIO!
So, never download a codec if u dont trust a source or webpage.
Play the video first. If there's sound but there isnt any video.
it's just some cloaking thing that makes the whole screen black.
And then it prompts you to download the codec. Use your brain,
cause if your player is able to play the sound, it's able to play
the video. If not it will have a (!) besides it.