Watch: Four Clips Of Cameron Crowe & Elton John Discussing Their Documentary With Leon Russell “The Union’

While on the surface it appeared as if Cameron Crowe laid dormant after 2005's "Elizabethtown," the truth is quite the opposite. The "Vanilla Sky" filmmaker wrote a Marvin Gaye film (still unproduced as of now) and a "Jerry Maguire"-like romantic comedy set in Hawaii with a spiritual element to it ("Deep Tiki," also unproduced), and in 2011, released two films: the documentary, "Pearl Jam Twenty," and the feature-length effort, "We Bought a Zoo" starring Matt Damon (which grossed almost $72 million domestically; not bad for a film which some called a box-office dude at first).

Crowe also debuted another documentary last year called "The Union," which premiered at the Tribeca Film Festival. The film is a look at the making of Elton John and Leon Russell's collaborative album of the same name, The Union, produced by T-Bone Burnett, and the documentary airs on HBO tomorrow.

Below we have four clips of the making of the film. Two interviews with Cameron Crowe about the process of shooting the film and what it was like documenting these two music legends. And two interview clips with Elton John, one of which reveals that John is extremely private and doesn't allow anyone to chronicle the making of his albums. But with Crowe, famous for his music journalism at Rolling Stone and his music-centric films like "Almost Famous," John evidently felt completely at ease. Check out the four clips below.

"The Union" debuts on HBO tomorrow, February 2nd at 9 p.m. ET.