What happens in Paranormal Activity 2?

theres a baby and a dog, and they film at night again, and the baby gets dragged out its cot, and its crawling on its own outside

Actually, PA2 occurs prior to PA. You get more history about Katie and the sister. All that was said before is skewed from what the trailers have shown, but in reality none of what was shown actually made it to the movie. Basically, someone in Katie's family sold their soul in order to gain power and repayment of the debt is the first male heir in the family (cue in the baby). Katie plays a small role until the end of the movie. All in all, you should watch it.