This rock and roll opus by director Brian De Palma has garnered a cult following, but still remains somewhat obscure to the general public. It tells the story of naive composer Winslow Leach (Finley) and his destruction and ultimate redemption at the hands of maniacal music mogul Swan (Williams). It's told in an epic style with references to many film and literature classics from The Cabinet of Dr. Caligari (1920) to Wilde's The Picture of Dorian Gray.
This film has something of a cult following, though it's somewhat unknown to people not versed in De Palma's work and rock and roll cinema. It's available on DVD and BlueRay and can be seen in full on YouTube. Part one is above, uploaded by bvseediermedia19.
Obscurity factor: 2 (known to many cult fans, available on DVD & YouTube, unknown to the uninitiated)