We have no idea how this guy on Youtube found this footage, as it doesn’t exist on the Extended Edition documentaries on the DVDs. In the original scripted ending to Return of the King; Aragorn was going to fight Sauron at the Black Gate. This doesn’t happen in the book, so people would’ve probably rioted when it happened. Luckily, Jackson came to his senses and digitally removed Sauron and replaced him with the Cave Troll that Aragorn fights in the finished film. In the video below, you can see the fight as it was originally filmed.
Unfortunately, the video has disabled embedding so if you want to check it out you can do so on Youtube right here.