As the title of the video you posted says, this isnt a copy. This song was orginally titled "I Never Heard" and was written by Michael and Paul Anka then was given to the Puerto Rican Freestyle singer Sa-Fire back in 1991.
"This Is It" was just a studio demo that Sony(PHONY) renamed with the first words of the opening lyrics (coincidence much?) and threw it together with some backup vocals by the Jackson brothers along with some orchestration to make it more grandiose.
Sony did NOT get in touch with Sa-Fire or Paul Anka before renaming and releasing the song nor did they give Anka co-writing credit until after a surprised Anka was told about the song the day of its release and confronted them about it.
This demo was taken off the shelf and dusted off just to solely tie in with the movie and to generate more revenue for Sony. Since I believe the *real* unreleased songs were set aside by Michael to help support his children, Sony cant touch those along with his half of the Sony/ATV Music Publishing catalog. The man had real shrewd business sense.
Michael *never* intended to use this song. The decision to include this song in the soundtrack was made after Sony bought the rights to the rehearsal footage.
This is just an ugly and disgusting marketing scheme.
Regardless of this fact, I still love this song. Even tho the original was only a demo with Michael's voice and a piano, you can hear a lot of potential there.
I plan on downloading not buying the soundtrack because I refuse to line Sony's fat pockets any longer. But I will go see the movie.