I bought it. It doesn't show up in your GOG library when you do so. I guess there's no category for it. It's definitely not worth 9 USD. I mean this is clearly not CDPR pricing.
I must say that I'm disappointed in this. Normally i don't fuss about 4k and hi res audio. However considering this is a concert and available in a 4k download, surely the soundtrack should be of a higher quality than simply 320kbps stereo. Surely the 4k download should consider lossless 24bit and potentially a greater sample rate. I just find it strange that a 4k concert is just standard audio. Generally speaking, good video
As far as I know it does not. The concert is newer than the GOTY edition, and no new content or DLC has been added to the game since the last patch in September 2016.