The comparison to an air hockey table indicates the opposite to a vacuum. Air hockey tables elevate the puck by blasting streams of air up from the table surface creating a cushion of air for the puck to glide on. Perhaps by saying it is not a "vacuum tunnel" he meant it is an "air tube". :)

FTA: "In theory, this elevated tube system"

So, yeah. Not a tunnel.

My first thought was "Oh, so it's the thing he said it wouldn't be, just above the ground.", too. :P