There are three tugs that can be seen at 34sec, 1:24 and 2:46 in the video below. I'm not a huge follower of the show, mainly because it's not readily available for me to watch, so I really don't know how they do things. The problems people have with this incident is that Grant's right hand is almost always in his coat pocket, people seem to think they are acting bad and they didn't do what they would usually do and pull out their gadgets to do some detecting.
The first and last tugs, well I can't really notice anything suspicious going on, but the second collar tug, Jason makes a strange move that kind of syncs with the tug, looks a little suspicious, then again he could have just been moving out of Grants way.
Hope it's real, I really like the idea of being tugged by a ghost someday... and that was just a little nasty.
