Ah, right I got confused with that "blurry reflection look" and forgot that this video is only about lights. What a bozo I am!
I've never written SSR/cube reflection before -- it seems like you would have to turn off the lights before your SSR/cube reflection pass so you don't "double up" the reflections of the light, right? It Otherwise you would have one reflection from the analytic/punctual light model and another reflection from your SSR/cube reflection pass. Or is that not that big of a deal?
For cubemaps you turn off any direct contribution, correct.
Do you really ? I always thought you capture it n number of times to simulate light bounces ?
I'm assuming he means the emissive texture/sprite that's supposed to represent the actual "light emitting" part of the light. EG your sun disc representing the sun. In which case you'd want to turn it off for cubemaps or else you'd get a double contribution, one from the cubemap capturing the sun disc, and one from your analytic directional light. This doesn't, or shouldn't matter for SSR as SSR is hopefully just going to overwrite your analytic specular with more accurate SSR reflections of your emissive material (assuming it hits).
There are plenty of circumstances where you may even want to leave them on for cubemaps too. If the light is distant enough that its analytic solution doesn't contribute, you can certainly capture it in a cubemap (distant city lights or something).
And for actual light contribution otherwise, eg drawing point lights and etc. then you just leave them on for both cubemaps and SSR.
OH! And edit, duh. Here's the exact same thing as the area lights OP posted, but with source code and a permissive license and etc. etc. Also diffuse lighting at the same time, still no shadows though (raytrace analytic shapes/signed distance fields?) https://eheitzresearch.wordpress.com/415-2/