You might have first seen this in that Grindhouse double-feature movie by Quentin Tarantino and Robert Rodriguez in 2007 (Planet Terror and Death Proof). Along with Machete starring Danny Trejo, Hobo With A Shotgun is the second movie to made into reality from the mock-trailers featured in Grindhouse.
The original "fake" trailer, featured in Grindhouse (2007).
I LOVE this movie. It was made in 2011, but it looks like it was filmed in 1975. It captures everything that makes the exploitation films of the '70's a worthy entry into the Vintage Hall of Fame. Excessive violence, fake gore and acting ranging from excellent-to-bad make this one of the greatest nu-vintage movies you'll ever come across. Rutger Hauer gives the performance of his life here. It's a true sight to behold!
I'm pretty sure you can stream Hobo With A Shotgun from Netflix. It's also on Showtime a lot. WATCH THIS MOVIE any way you can, you will not regret it.
The REAL movie trailer (2011)