Dirk%20Nowitzki%20on%20His%20Remaining%20Time%20in%20the%20Changing%20NBA%2C%20%E2%80%9CWelcome%20to%20the%20League%E2%80%9D%20Moments%2C%20and%20Becoming%20a%20Champion%20%20%7C%20Winging%20It%20(Ep.%204)