Actually, his example won't work (although at first I thought that it would, too). Based on the help for the Start command, the first parameter is the name of the newly created Command Prompt window, and the second and third should be the path to the application and its parameters, respectively. If you add another "" before path to the app, it should work (at least it did for me). Use something like this:
start "" "c:\path with spaces\app.exe" param1 "param with spaces"
You can change the first argument to be whatever you want the title of the new command prompt to be. If it's a Windows app that is created, then the command prompt won't be displayed, and the title won't matter.