I didn’t understand “a whole lot of middle.” Is "a whole lot of something" an expression?
The speaker means this to be a metaphor. He says, "life only really has one beginning and one end. And the rest is a whole lot of middle." "Middle" here is likely referring to the events of life, including the good and bad. "A whole lot of" something is a commonly used expression. It is used to emphasize or exaggerate the quantity of something, which in the case of this video, is "middle." Ex: Starting a business requires many things. A good idea, investment, time, and a whole lot of luck. Ex: I was a naughty child. You needed a whole lot of patience to deal with me.