I know - this has been covered before - but is it just me or does it seem like every time the DJI GO app gets updated the video goes to hell?  

It depends upon which video you are talking about. There is the high quality video that is recorded to the SD card in the aircraft, and there is the low quality feed sent back to the RC unit and displayed by your phone or tablet, or live view. If you are referring to the live view, the quality of it is determined by your phone or tablet. If it is fast enough to process the images, you get good pictures. If it is not fast enough, it looks like crap. You probably need a better phone/tablet.