For some obscure reason, I have some video files I downloaded from YouTube as FLV rather than in another format. I would like to re-mux them into, say, MKV (Matroska). When trying to use ffmpeg, I get a Unsupported video codec (7) message. What should I do?
I'd like to be able to do this both in a command-line tool and through a GUI but either is fine.
My OS for the purpose of discussion is Windows XP SP3.