Complex sentence: Timothy Bottoms' younger brother Sam came along to stay with his brother for a few days as rehearsals started in Archer City, and Bogdanovich saw him sitting on some stairs and asked him if he could act.
Split into simpler sentences: Timothy Bottoms' younger brother Sam came along to stay with his brother for a few days as rehearsals started in Archer City. Seeing Sam sitting on some stairs, Bogdanovich asked him if he could act.