Has anyone heard of getting caught speeding on video and pulled over for it?

About a week ago I was pulled over on I 270 in Maryland for going 80 in a 65. I believe that I was going this fast at one point but when I ped the state trooper I was behind cars in the slow lane going the speed limit. The officer pulled out behind me and followed me for a minute and then pulled me over. He told me that I was caught on video a few miles back going 80. I got a $160 fine and 2 points. I've heard of traffic cameras where you get a ticket in the mail but I have never heard of being caught on video like this and I can't find any stories of this on the internet either. I'm planning on going to the trial just to clarify that this is how I was caught. Also, I think I might ask to see the video. Has anyone else heard of this?