I am thinking that may be it. I just flew today in another location about the same distance as yesterday and my range appeared to be way better but still blocky video. I am thinking it may not be a loose antenna but a video processing thing. I have a Samsung Note 5 but maybe a lot of processes are running at once. I have heard that can be an issue with this phone.
I had a nexus7 2013 edition and once the GO app reached a certain size along with added processes, there was permanent issues. I was determined it was a app problem until my beta admin from the beta team helped my at great length. The fix was I replaced the nexus7 with a Nvidia K1 Shift. And it is a badass tablet!