What did the priests know about the Messiah and the Old Testament prophecies?
The priests knew the surface-level facts of the Old Testament prophecies but not the deeper details. When Herod asked where the King of Israel would be born, they did not know and had to search the Scriptures, then answered Bethlehem.
Les explains that Israel should have known who Jesus was because it was in the Old Testament, but they were ignorant because they did not bother to study. The priests knew the surface-level content, but they had not gotten down into the nitty-gritty of the Old Testament prophecies. When the wise men came to Herod asking about the King of Israel, Herod called up the big wigs of Judaism and asked where this King was to be born. They did not know; they had to search the Scriptures. They then found that the Scriptures said He would be born in Bethlehem. So they could have known, but they didn't. Les compares this to America today, saying America is no better.