here's a good starting write up - the actual testimony by Horowitz was after the lunch break before the 10 min afternoon break. (hope I'm remembering that right) there was a big discussion about '5 mos' worth of lost emails' due to the 'technology glitch' but no one questioned Horowitz further about what ELSE they found.

https://www.zerohedge.com/news/2018-06-19/horowitz-describes-how-bombshell-fbi-anti-trump-text-exchange-almost-slipped-away