Several of the videos show fences with no ground lines whatsoever, ones with ground lines have them rolled to *under* the fence, inside the first element of the fence. The purpose of a ground line is to help the horse see the base of the fence and judge the take off point; a rail under the fence, or behind the first element, creates a false ground line and is likely to trick the horse into jumping too close.
In the video "Lexie and Cowboy 1" the rider is jumping the makeshift oxer backwards, with the higher element in the front.
I greatly dislike the skinny, hollow PVC rails. They're hard for the horse to see, tend to fly up and/or shatter when hit, rather than dropping straight to the ground like a solid wood rail.