I was the one who made that video. I have a Blender script for importing the .mch models, and another script for reconstructing a .mch (mostly, I have to add the texture section manually) from the imported model. After importing, I delete the mesh, then make a new mesh using the same names as the old mesh (the export script refers to things by the names assigned by the import script), keeping only the skeleton and any animations that were loaded.