One of which is you can see what files are "parents" of the sample. In this case, there are a bunch of zip files that contain this file, all named Immunity Canvas or similar. Canvas is a pentesting tool where they publish exploits, so I guess he's saying you can attribute it to Immunity.
And yes, VirusTotal lets you download the file if you pay. It's the foundation of the "threat-intelligence" industry :)
I remember Immunity advertising about an exploit for spectre they have, and it's easy to find:
Very likely that this is what the top poster found.
Indeed, so it is critical to never upload any binaries to them that you do not have full permission to redistribute. Nowadays they are very open about the sharing, but in the past this was kind of hidden.
Not sure if that's good, bad, or something else, though. :)