Unfortunately, at this time that I am making this video there is no official 64bit ARMv8 Operating System(OS) for Raspberry pi 3. It seems that Raspberry manufacturer forced armv8 1200 MHZ board to work as ARMv7 ! and this gonna give you an error during installation of GNURADIO on Raspberry pi 3(probably GNSS-SDR too) so in order to resolve this problem we inspect all those OS and then came into the following instruction in order to install this software. feel free to ask questions. unfortunately the image of this OS is 8.5GIG and I didn't find any server for this big size files and high bandwidth for all users. have fun!