Why does Les connect the valley of Shavuah with the same location as Jerusalem?
The link is made through the name: the same last five letters are pointed to as belonging to Jerusalem, so the valley of Shavuah is treated as the same little village and area. The passage places Abraham's return near present-day Jerusalem.
Les explains this while pausing the discussion of the high priest and going back to Genesis 14. Abraham had pursued the kings who overran Lot's hometown of Sodom, conquered them, and brought Lot and his family back. On his way back, in the area of present-day Jerusalem, the king of Sodom met him at the valley of Shavuah, which is of Sodom. Les says he always points out that this is the last five letters of Jerusalem, so it is the same little village and the same area.