The phrase "original widescreen" means that something was initially produced or designed to be shown on a bigger and wider screen than the standard or traditional size. Full definition
The disc closes with On the Waterfront's original widescreen theatrical trailer (2:42), which raises expectations with its promising scrolls. (dvdizzy.com)
More important than that is at last the film is treated to a respectable feature presentation, with original widescreen framing and terrific picture and sound. (dvdizzy.com)
But that, of course, is problematic on home video, and it was quite apparent to those who saw the film in cinemas that the original widescreen transfer of Se7en did not accurately recreate the intended look, mood or intention of the film. (dvd.net.au)