Please let us know how it has been debunked.
This description matches the declassified PRISM documents, the description in Snowden's leaked slides, US law, the miniscule price tag in Snowden's slides, and the description of a specific PRISM integration I heard from one of the implementers (possibly one interviewed in the nytimes story).
XKeyscore was a program to analyse data siphoned from wiretaps. This is what caused that infamous ppt slide "SSL Removed Here ;-)" which, among other reasons, caused Google to start encrypting all of the inter-data center links.