The video DOES show where the wall is being built from the Pacific "Sea" to the "Sea" of Mexico. So your first sentence is incorrect.  Yes machines are used to fabricate each "fence post" on sight.  And, yes, machines are used because this "picket" fence is 26 feet taller than the "home owner" installed version.  Those machines are testament to "American ingenuity".  Glad you enjoyed the video.  WWG1WGA!