I was watching this, then realized that it's actually not necessary for some GPS receivers. If you hook your GPS receiver up directly to a com port, then you can do a live feed into Google Earth. Check out the options under Tools>GPS. You can also import NMEA and other files there. These options are nice, since they automatically support more formats of NMEA data than just GPRMC.
Great video and very helpful! I am setting up something very similar, and I was wondering if you could tell me how to modify the code a little. My receiver is already printing one nmea RMC sentence per second to the serial /usb port, so I just need to read the incoming strings and not interface with a device. I am also unclear as to how (and where) to set up the .txt file for python to write to. Any guidance would be most appreciated!