That's very interesting. What you found is a teaser, not a proper trailer. Apart from a couple of shots the entire thing looks like scenes from the LOTR trilogy, with perhaps a couple of outtakes.
To the best of my knowledge, there is not even a script, let alone a director for the movie, so I find it difficult to believe that any actual footage was filmed. A teaser like this one may have been prepared as a presentation for the New Line directors, to persuade them to give the final go-ahead for filming