For those who don't know, the very limited edition Ghostbusters Ultimate Collection included a new (old) version of the original 1984 movie. A work in progress version.
For those who are unable to find a copy of the entire Ultimate Collection, a Reddit user has made just the workprint cut from this collection, a 4.7gb file available on Google Drive, it includes the commentary track.
I don't know if I'm allowed to post links so you'll have to look on Reddit yourself. The file was made available a year ago and is still there which leads me to think there isn't a copyright issue.