Dat effect

I mean he's not being an asshole its just that it really is over sharpened and not very well executed i guess it's the way he put it.
If you really want to do it:
-get a 20px round brush with a color and make a line or a curvy line
-smudge that line with a hard round brush with a pretty high strength
-go back in and smudge more with a small brush with 100% strength to get the line effect
-take those layers to you with the smudge and sharpen them once or twice
-to get the lights take a medium sized soft brush and make a dot on your image
-make more and change blending mode to:color dodge, lighten,linear dodge

smudged lines