Those episodes were definitely saved - Starmaker released ten of them on video in the ‘90s as “The Best of SNL 1975-80” Volume 1-5. Bumpers and music acts were edited out but each episode followed the format you describe and had a 1979 or 1980 copyright at the end. I watched them a few years ago...
Was this ever done in reverse? European TV productions released theatrically in the US? Closest I can come up with is the Beatles’ Magical Mystery Tour film.