Complex sentence: We see Louis again as a young man sitting in a train, staring out the window at the blurring railroad tracks, as Really and Sincerely by the Bee Gees begins to play.
Split into simpler sentences: We see Louis again as a young man, sitting in a train and staring out the window at the blurring tracks. "Really and Sincerely" by the Bee Gees begins to play.