Are you sure they're buying from Akamai? I heard they were getting their bits from LimeLight and Level3.
They dropped Level3 and now use Akamai and Limelight. Their contract with Akamai states they must give Akamai at least 51% of their business.
This is 100% fact there have been press releases and tons of information from completely reliable sources about it. If you still care use Google to easily find the proof.