Are you referring to the one that Topher Grace did?
For anyone who says "that name sounds familiar" - he was ostensibly the star of the late-90s/early-00s television show "That 70's Show." He was also Eddie Brock (Venom) in the last of the Raimi-directed Spider Man movies. Which was a really odd bit of casting for me, but whatever.
Anyways, yeah. Apparently he was/is a Star Wars superfan and got interested in the process of film editing. He decided to edit all three of the prequel films into one movie, and held a one-time (that I'm aware of) screening event for friends, family and press. Due to concerns about copyright, etc. he never actually made it available beyond that one screening, so if you saw the actual thing it would be kind of interesting in that it would imply a leak or what have you.Here is an article
that summarizes the creative decisions he made. Just as a warning, it is a relatively complete synopsis of all the creative decisions made in Grace's cut, so if you have found some video of this and want to go into it fresh, you might not want to read about it.
Edit: Actually a quick Google search tells me you're not referring to directly that one! Although the creator did indicate they were heavily following the blueprint of Topher's edit (I assume based on similar synopsis articles to the one I linked above).