Request: A suggestion for idiots
I know it's fairly obvious (it is to me now anyway) but maybe you would consider using a radio button group instead of tickboxes to select the output format? I unchecked all of them and obviously nothing was outputted, where I think you should force the user to select one of the options (vtx, classic etc) to avoid some head-scratching trying to figure out why it wasnt working. Or maybe flash up a dialog to tell them that nothing will be output if they don't select one of the options.