Hmm... you don't really see people searching for codecs these days. Unless someone is still on an ancient OS, they're going to have all of the codecs they need--and even then, all they need to do is get something like VLC, which has become wildly popular. I'm pretty sure Windows Media Player even plays Matroska now, but I'm too lazy to check. I haven't run into codec problems in many years.
You could try gearing it toward codecs for ffmpeg--people still search for codecs in that context--but those are murky waters. Some of those patent holders are pretty aggressive. Nobody seems to be willing to touch MP3 with a ten foot pole.