Movies that lack big-name actors and that are shot with shaky, documentary-style camera work don't tend to have huge opening weekends at the box office -- except for in the last two weeks. Following the October record-breaking $50 million debut of 'Jackass 3D' last week comes the similarly astonishing premiere of 'Paranormal Activity 2,' which earned an estimated $41.5 million to open in first place.

The original 'Paranormal Activity' became the most profitable movie of all time last year (made on a budget of $15,000, it grossed $193 million worldwide) through a canny release strategy that involved clever viral marketing and a platform release pattern that built up word of mouth over several weeks as the film expanded across the country. The weekend it opened wide, it took in a healthy $19.6 million. This weekend, however, the sequel used a traditional wide-release pattern (opening on 3,216 screens nationwide all at once), so pundits were predicting an opening in the range of $20 to $30 million.