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Is this what you're referring to? From the transcript:
Turning what could have been a minor updating to let the U.S. eavesdrop on purely overseas calls that happened to come through switching stations, turning that into unchecked power to listen in on American calls to or from overseas as well.
This refers to foreign-to-foreign calls that pass through the US. This is the minor update you've heard about that wasn't covered by FISA.