Which actor delivered what has since become a historically-prescient line: "Wait a minute. Wait a minute. You ain't heard nothing yet."

The actor thatdelivered what has since become a historically-prescient line: "Wait a minute. Wait a minute. You ain't heard nothing yet."

was:

Al Jolson.

Explanation:

Al Jolson was an American actor, comedian, and singer that once was considered the world's best entertainer. He acted in The jazz Singer in 1927, it was a movie about a singer who comes from a Jewish background and struggles to become a famous singer. This movie was the first one in which music and lips movement were aligned. It started with the phrase: "Wait a minute. Wait a minute. You ain't heard nothing yet."

Al Jolson