Usually videos can’t even begin to convey how frightening a roller coaster can be, but I have been searching around for some scary roller coaster videos. Actually, the video of Saw: The Ride in the previous post did a good job of conveying the fear through the lack of any screaming.
My preference is for POV (point of view) videos, filmed at the front of the ride, and in fairly high quality, to really feel the scariness of a roller coaster. Vertical drops also do it for me, like this video of Oblivion at Alton Towers:
Personally, I find the videos filming the faces of the riders rather than seeing the ride ahead do very little more me. How about you?