The big take away from this video is that Sony 200-600 and Canon RF100-500 take extenders surprisingly well, which @AlanF has shown in the Dragons and damsels thread as well.
Jan also shows the quality difference between cropping and extenders in a few situations, including downscaling a photo shot with extenders to the same amount of pixels of the cropped picture. The overall advice is still "It depends", but with autofocus at f/22 and much improved noise performance and reduction in post, using extenders isn't as bad as it was 5 years ago.
