I watched the interview and found her to be absolutely credible. Her facial expressions alone (not a good poker player) are those of a person who believe so strongly in their statements that they don’t bother even trying to put on an objective demeanor. When asked if Clinton lied she was nodding, smiling and said Yes without a milliseconds hesitation.
And just because the name Sarnoff is so unusual I checked. Conchita Suarez married one of the grandsons of David Sarnoff in 1984. He was a radio entrepreneur who rose to fame by receiving messages from the sinking Titanic and built and ran RCA for many years. Just a little historic tidbit for those interested ;-)
The interview: https://www.youtube.com/watch?time_continue=5&v=YL6soUcE_Vc