That is an adult in Tom's video. I have had many of these fantastic animals over the years. The smallest adult I have ever had was a male that never got over 4 1/2 ft long, and pretty skinny. The largest was a female at just under six ft long and quite a bit thicker. That biggest girl was still noticeably smaller in diameter than an adult ball python. Over all they are similar in size and girth to a California kingsnake. Maybe a touch thicker.
Keep in mind that these animals take a LOT longer to reach maturity than many pythons. With those that I raised from hatchlings, I have not had successfull breeding with males until 3 or 4 yrs old and females, not until 5 yrs. Feed sparingly and be patient.
Handle them A LOT and you will have great pets. Do not handle them and you will loose blood!
Tom has GREAT stock. Some of the best I have seen. (outside of MY house, of course!) Here are pics of my favorite, current breeders. Male - 7 yrs old, Female - 6 years old.
http://i83.photobucket.com/albums/j283/Tsuba_1/Tsuba.jpg
http://i83.photobucket.com/albums/j283/Tsuba_1/Kashira.jpg