It's absolutely not the original shooting scripts. Multicam sitcom scripts have a very specific style of formatting, and these are just missing details they would contain in terms of scene descriptions, etc.
But this also isn't just a transcript of subtitles or closed captioning. It's full of things like:
> KRAMER: [glues the article back with his own saliva and puts the magazine back on the table] When you're done, let me know.
> % Jerry shows Elaine some movie from the Adult section that's probably % called "The Sperminator", or something...
So fans transcribed these and then tried to fill in the visual details as well?
What a labor of love. I'm curious if there's a specific term or name for this type of transcription-with-visual-details.