I saw that particular episode just the other day - first time I've ever seen it. I thought it was highly convenient that a team of ghost hunters managed not to get the whole of that piece of paper with the cross on it in shot. That was really shoddy. As a sceptic, my natural inclination is to say, 'I couldn't see the whole of the paper, so I suspect someone manipulated the situation via the end we couldn't see.' If it was a genuine act, then it was indeed pretty freaky though! As Lennon says, they do seem to see orbs a lot. Personally, they seem to be little more than motes of dust, possibly in the camera itself, that have caught the light from what I saw.