It wasn't that he gambled away his land that was important(that was later in the family history) but rather that Edward IV became king.
The premise of the program was that Edward IV was illegitimate and that if you assumed that he'd not taken the throne who would have been the rightfull king.
Of Course Henry VII had the most dubious claim to the throne and he overthrew Richard III.
Had Edward not become king then George, Duke of Clarence would have become King - he was executed for plotting against his brother Edward.
It is however quite possible that had George become king all that would actually have happened is that Henry would have overthrown him at Bosworth and not his brother Richard.
Good program all the same - it was called Britain's real monarch
http://www.channel4.com/history/microsites/H/h istory/i-m/monarch.html