Hi blindfoldjump, 18:40 is what's called an "untrim" - you can remove a trim curve boundary from a surface if you have a hole there (meaning the edges only belong to one face instead of shared between 2 faces), which is opened up by deleting the interior side walls of the hole. When you have something like that you can select all the edges making up the trim boundary and hit delete to remove them. See here for more information: http://moi3d.com/forum/index.php?webtag=MOI&msg=444.4 and I think it's also covered in the object repair tutorial here: http://moi3d.com/forum/index.php?webtag=MOI&msg=446.17
42:35 is I think a shortcut key that runs a script that deletes half the object and runs mirror on the main one, the objects probably have some specific names that the script looks for.
