Dougie MacLean, a Scotsman, created the original music "The Gael". Trevor Jones adopted the music for Orchestra and it became the theme song for the historical fiction novel by George Fenimore Cooper (an American author). As you correctly pointed out, the music was not inspired by native Americans or their music. If anything, it might be described as Celtic. The performer in the video is from South America and confuses the Indian tribes on the east coast with the plains Indians. Moreover, the headdress is normally reserved for ceremonial practices and is not normal attire. Tribal members can speak with more knowledge on the subject. The version of the Gael composed for the movie perfectly fit the mood of the movie. The book is a nice read, too. It's a creative performance but it's too bad that so many people around the world are confused about its origins. They don't know about north American tribal music and art; American literature; Celtic influences in the American colonies or Scottish music.