I was reading Wikipedia's list of unusual articles, which I strongly suggest you check out, and found out about Nothing Lasts Forever, a completed feature-length film with Bill Murray and Dan Aykroyd that was postponed by MGM and never officially released theatrically or on home media in the US. I'm surprised the LMW doesn't already have an article about it. According to the article, it was uploaded to YouTube in 2014, but was taken down by Turner Entertainment and later broadcast on Turner Classic Movies. I don't know if it's been seen since. Even if it counts as found, we've had plenty of articles on formerly lost media that was found before the wiki even came into existence.