It is mentioned "if unable to get the Google Earth Plug-in working on your computer, you may skip this problem set." Does this means pset8 is optional??
Remember that you can do Pset8 if you have a second computer (either desktop or laptop) running on either Windows or OSX.
Just use the appliance as a "server", the second computer (with GoogleEarth plugin) as a client, and ollow the instruction posted here to connect to the appliance using another computer.
Warning: this answer is related to version fall 2013 of the course
Yes, problem set 8 is optional. Quoting the professor's comment on a post on the course's Facebook group
In pset8, I am unable to get Google Earth plug-in working on my computer then can i skip this problem ? If yes, then it is necessary to inform CS50x team ?
Prof. Malan's Comment:
No need to inform.