First of all you can't download without purchase. You can purchase the complete five seasons of "Tracks Ahead" by going to:
www.HistoricRail.com .......or calling toll free 800-261-5922.
Actually, there are six seasons available from the following site. Season 6 has 5.1 surround sound. I need to order that one myself, already have the others.
http://www.tracksahead.net/Shop/Tracks_store2.htm