William Castle's contraptions were installed INSIDE the theater showing the movie. The patrons entered in knowing what they were going to get.
This "viral" marking is film exploitation in what is known as a publicity stunt. Stage an event in public to generate press.
Looks like it worked.
Then again journalists think they've done their job if they have spent the afternoon looking at youtube clips and posting what they saw.
Saw House on Haunted Hill as a kid, and can still remember the skeleton that came out from behind the curtains on stage, and traveled above, on a wire across the theater. It was during the scene where Vincent Price brings up the skeleton from the acid bath to scare his wife.