This isn't about the Volvo, it is about the Renault. The Modus is a Toyota Yaris/ Chevy Aveo sized car. So, it is pretty small. The crumple zones in a car are there to reduce the g-forces. You do not go from 40-0 in an instant, the car crumples in front of you so that that you have more time to come to rest, reducing the g-forces you face.Strength is only half of the safety of a car. The other half is the g-force. The lower your weight compared to the car you're crashing into, the more g-force you have to deal with. Which is why no matter how well designed a small car its, its never going to be as good as a (well designed) large car.
This video proves nothing btw. That Volvo was ancient. And the Renault really wasn't that much smaller.
A well designed larger car is always going to be statistically safer but what this shows is that a modern small car is not a death trap.