The movie opens in Los Angeles on Friday, in three Laemmle theaters (in fact, it's a Laemmele/Zeller Films release). And it also had opened in New York. A Boston open is coming on June 21, so I'm suspect there will be other cities, as well.
I can't find a clip from it, but here's an extended trailer, longer than the one I embedded before. What's nice is that this has more footage of his athletic endeavors here, and also clips from two of his three TV specials, him on the flying trapeze in the circus, and getting walloped by John Wayne when he tried acting in Rio Bravo. Also, if you look closely, you'll see him in his most famous moment which he describes in Paper Lion, falling to his knees in an exhibition NFL game. When they made the feature film version, they Hollywooded it up and made it too goofy -- this clip is the real thing.
(Know that this trailer only runs about 2:50, despite what it shows. There's about 40 seconds of I don't know what that comes after.)