Non-acting acting
I really really don't like found footage genre films as the wobbly camera usually makes me want to hit someone... anyone. This didn't have that and I found overall the acting was really convincing with some, what I would call, Meryl Streep acting (the type that makes you know you're watching an actor) that spoiled it. It's hard to find actors who can genuinely act natural. In particular their biographical videos where all solid. I was impressed.
I'd just like to add an embarrassing side note for the anecdotal (I hope) content. The other day I watched Cropsey. I was TOTALLY blown away with the level of acting and how EVERYONE had nailed it. I found the attention to detail in the aged news reports and worn papers beyond perfection. Then at about the 20 minute mark I finally realised I was watching a real documentary. Pretty dumb I know. I kept waiting for the "action" to start i.e. the film makers going back into the asylum and getting knocked off one by one.