I heard this story in three different marine biology labs going back to the 1980s (prey type differed depending on location). All were "it happened a few years ago", it was "caught on camera back then" and no actual eyewitnesses who could attest to seeing the film.
Then again, I've also had to clean up a couple (witnessed) octopus escapes, though not with the full "got out, got prey, got back in." So they are at least somewhat prone to roaming.
Woah, wild. Well, in my case, I don't have the video footage because this was 10 years ago, so yup this falls right into the same hearsay category as those two.
I would guess that Octopi just tend to do this. They really are smart and can fit through crazy small spaces.
- http://belizeadventure.com/2013/08/octopus-facts/
- https://www.tonmo.com/threads/midnight-tank-escapes-fact-or-...
Edit: this is not to call you out for you story, it's very possible that this happened at CHS aquarium, I'm just wondering the origins since it's such a fascinating and strange story.