The title of this thread is saying "best music out of a vike movie", Dont use songs from other vids, find your own.
Make sure you choose a song which compliments the riding style in the film. IMO a riding video is 10x better when it is in sync with the song, so if you havent started editing yet etc. choose a song that suits the riding style and build the movie around the song, (keeping in mind accents and moods).
So what style riding is it? maybe we can give some better suggestions then.
hope that helps.