That's a great video and very helpful, but I'm not clear how it shows that the car starts in 1st. How do we know that we're not looking at 2nd, 3rd, 4th and 5th gear?
If the car does in fact normally start in 2nd gear, I wouldn't say that 1st is reserved for heavy loads, I'd say that 1st is reserved for when you stomp on the gas.
I'm not taking sides on the 1st, 2nd debate- I don't have any meaningful evidence either way. Given BMW's hyper-focus on fuel economy, I tend to lean toward the start-in-second camp though. With normal driving, starting in second would improve fuel economy. Dropping down to first on full-throttle allows for impressive 0-60 numbers as well.