Interesting technique that I tried on a picture of the Point Reyes lighthouse where the sun was on the lighthouse so made it a bit too bright for my taste. This was a good way to reverse the lighting so the lighthouse was darker and the foreground lighter. I used one of the photographic toning gradients (selenium) that seemed to work in the soft light blending mode. It did overbrighten some areas so I toned it down by painting on the mask. Just for fun I tried the same gradient on a gradient map layer (which is a good way to convert to black and white - or in this case selenium) and dialled the opacity down to 30% to bring some colour back.
... Found the radial gradient process a bit fussy, but that's probably just me. ...
Nope, it's me too as I posted earlier
Personally, I would use the Gradient Fill adjustment layer for special effects, not for highlighting parts of an image as was the purpose in the video. I find using Levels and Brightness/Contrast adjustment layers with masks more flexible for highlighting elements in a scene.
Thanks for joining in the Challenge Tony. If you don't mind me saying I prefer your After image to the one with the Gradient Map Layer applied because (on my screen) it has that little bit more colour than the latter. Looks like a lovely spot and going by your photo has plenty of visitors.