I don't think it was saying "motherforgeter," but there's certainly something at 1:02 that doesn't sound like you.Also, what are those high-pitched sounds heard at several points during the video?
Probably just your mind playing tricks on you. You were told the place is haunted so you're expecting creepy stuff like disembodied voices, and so you end up hearing things that aren't there.
Were you able to hear the recording?