Menard says he saw BOARDINGHOUSE at the drive-in, though, so apparently it was not SOV, although everyone seems to believe it was.
I don't know where that rumor about boarding house started; even IMDB lists it as having been shot on video and transferred to film.
Even a full inch video camera and deck could not produce the quality necessary to show it on a drive-in screen. At the time, anyway, a full inch deck and camera would have been more expensive than a 16mm film camera.
If you all want to understand a little about video, digital, and film resolution, you can read an article of mine that will explain a little about it in layman's terms here: http://aninstantintime.com/articles/evolution.html
The only thing I can rationalize about how the rumor started is that Boarding House uses an outdated visual warning device for when the upcoming scene is going to be gory, so you can supposedly turn your head, not see the scene, and then think that it was actually gory rather than the joke it was. That segment of a gloved hand flexing may have been shot on video and used for the film.