The example is what is given in the text, but the exact location that the DVD contents appear can vary according to the distro and desktop you are using. The example of /media/LXFDVD156 is the most common location, but if the disc's contents show up elsewhere on your system, such as /media/cdrom, change the command accordingly.
Unfortunately, the security policies used to mount DVDs in most systems mean you cannot simply click an icon on the DVD. This would be ideal as there would be no need to know the exact path, but most systems mount DVDs with the ability to run programs and scripts like this disabled. Re-enabling that requires the terminal and knowledge of the disc's mount point, and if you have that you may as well run the script as described.
"Insanity: doing the same thing over and over again and expecting different results." (Albert Einstein)