HUGE plotholes

I'm amazed no-one has spotted these ones yet. About halfway through the movie, there's a scene where Thomas shows his mother the video footage of her doing the MARON scribbling. All well and good, but it pinpoints a serious logic problem earlier in the movie. The footage from the living room and the bedrooms of Samantha and her mother prior to the scribbling moment clearly shows the ghost doing strange things - knocking the crucifix off the wall, turning the TV on etc. Yet our heroes clearly had an agreement between themselves not to watch *that* footage, because they spend ages bickering over whether the crucifix fell off the wall by chance. A look at the tape would have answered that question instantly and definitively, but...they didn't even think "Hey, we've got video of that happening!", let alone actually watch it. There is no evidence that they did so at any point. So, we are faced with a situation where someone takes great pains to set up elaborate audio-visual surveillance of a very specific area, but when faced with an occurrence precisely in said area whose cause/origin can be determined by viewing said surveillance...decides not to view it. That makes NO BLOODY SENSE.

Also, on two occasions, the 'demon' rings the house's phone in the middle of the night. Two problems here - the phone is very loud, and rings for ages in an environment that is in otherwise total silence, yet none of the three hear it or are woken by it. And secondly, yet again, Thomas doesn't watch the footage he has taken such great pains to create, as he expresses puzzlement at the demon's answerphone message when he plays it back the next morning. Ah, but maybe he hadn't checked the footage at that point, you might say. Sure, but given that he never mentions the living room's TV remote moving by itself and then turning the TV on at *any* point after the events, it's clear he HASN'T LOOKED AT ANY OF THE FOOTAGE UP TIL THAT POINT.

The main logic problem is why Thomas never told the cops after the killings that he had hours of tape showing truly extraordinary paranormal events; events, moreover, that would tend to exonerate him at least in part. But everyone's spotted THAT one.