Definitely needs work.
Though not really necessary, some localization would put polish on this.
Implement Drag-and-Drop!! It's annoying as hell to search for a file via browse, when the window and file is right in front of you.
Fix up the "help" and about menus, as well as others. The author left the default "NewApplication" as the title throughout the menusystem.
It is nice not to have to go to the Terminal to do basic matroska extraction and exploring, but this was a rather lazy attempt.
Fix all the minor stuff, and even though it's a one-trick-pony, it will still be worth having, if idiots keep insisting on making stupid matroska video files.
On first use, it saved me about 5 minutes of mucking about with one matroska file in the Terminal. Repetitive use will save hours.
Maybe somebody will eventually create a one-step Matroska to MPEG4 or XVID avi file converter that actually works, and nobody will ever have to deal with this crap ever again ^_^