Questions raised about Saudi oil reserves

This topic has been in the news because of a Wikileaks release:

The cables, obtained by WikiLeaks, urge Washington to take heed of a warning from a former Saudi government oil executive that the kingdom's crude oil reserves may have been overstated by as much as 40 per cent.

US diplomats reported that Sadad al Husseini, the ex-head of exploration at Saudi oil monopoly Aramco, "disagreed" with Aramco's analysis that it had reserves of 716bn barrels that would rise to 900bn barrels in 20 years.

The video from Al Jazeera reports the data, then adds a brief interview with a the former head of energy studies from OPEC, who indicates that the doubts raised in the cables are not really news; this question has been asked by oil analysts for many years, and the question of reserve capacities applies not only to the Saudis, but to other oil-producing countries as well, since independent confirmation of such data is generally not available.