Tear drop travel trailers, do they sway?

I wish I had gotten my wife to video what I saw last year. We were heading camping, and caught up with a truck doing about 45mph on the interstate. It was a F-150 pulling a 4x8 utility trailer with a Harley on it. The bike was at the back of the trailer. He kept speeding up to around 50, and that trailer would start swaying, and pull that truck all over the place to the point he would cross the lines on both sides of the lane, looked just like that little car in the video. I followed him for awhile, I was a nervous to pass him, It was my first trip with a new camper. If he had put that bike on backwards at the front of the trailer he would have been fine. It is all about the loading.

I pull a 32ft TT, and I have no sway. I do get a push when a truck passes me, but with proper loading and sway control, it should not be an issue.