On this podcast of Chronicles of Josephus, Michael Miano brings us through details regarding Josephus' mentions of Biblical celebrations of Passover, especially noting how it was understood that God moved mightily and demonstrated His faithfulness to His people during that feast.
Other links for more information:
http://www.josephus.org/Passover.htm
https://www.bible.ca/revelation/Bible-Only-Revelation-Commentary-Josephus-Chronology-Destruction-Jerusalem-First-Jewish-War-70AD.htm