mintyy - don't blame you.
It shows a cyclist going very fast, intercut with his mother's very moving explanation how she wants people to see what an accident is really like, how she knows he was going too fast, but she'd urge both drivers and people on bikes to slow down and to try to anticipate what each other might down.
You see a single-carriageway road from the perspective of the guy on the bike. There is a right-turn lane in the opposite direction (ie., turning from the other side of the road, so cars in that lane need to turn across the path of traffic going forwards on your side).
The guy on the bike sees a car in the right-turn lane. The car moves slowly fowards to turn right, and as it does so the biker sees he hasn't got time to stop, shouts, and hits the car. You don't see the collision, but he's obviously been flipped into the ditch.
The car driver doesn't have right of way and should have stopped, but would have been expecting traffic coming on to be nearly forty (?) miles slower than the bike was going.