The Aluminum Falcon said:

Hey doubleofive, I noticed that on this comparison here, you talked about the different scan lines in the strangling scene. In fact, the dot pattern (caused by vertical lines) showed up as early as the 1989 Mitsubishi Special Widescreen Edition pressing, prior to the 1993 Definitive Collection. You can see a screen shot of a transfer here. It's possible that the JSC just lacked some vertical scan lines... and it was always there.

EDIT: I just checked the theatrical Betamax bootleg and it too lacked vertical scan lines so it was the horizontal pattern. Has Puggo released screen shots of that particular scene?

The dot pattern has been visible on video releases earlier than that, as early as 1985 on the US Pan & Scan LD for example. Like I have said before, these are most likely shortcomings in various video transfers and not an actual visual change done to the film.