Well, VDub is refusing to open the file because it doesn't know what an mkv file is, and AVI-Mux is opening it but refusing to remux it, giving the wonderful error: The user is too stupid. The user ...

An abbreviation of Matroska Video, MKV is a digital video file format that supports various types of audio and video codecs. The multimedia container is also commonly used by the anime fan-subbing ...