If you're not as old as I am, you are probably unaware of the 8mm home movie market that existed from probably the 1940s or so through to the 1970s, which was finally killed off by the home video market! I have fond memories from my childhood of going to Kmart with my family and seeing this dazzling display of 8mm home movies for sale... and after all, that was about the only way you could watch movies when you wanted to see them (even if they were edited for length, often silent with subtitles, and sometimes in black and white even if the original movie was in color).
As you can see above, both Batman movie serials received the 8mm or super 8mm treatment... but I'm not sure what that last one was... was it a edited-down Adam West episode, or one of the Filmation cartoons? Unfortunately, the seller didn't (or couldn't) say.
I know, you can't really see anything here... the seller said it was the 1966 movie, but I strongly suspect it was a chapter of one of the serials!