How much fuel did this Boeing 787-9 have on board for this flying display?
Looks like he is zooming after taking off: gain as much horizontal speed as he can, then pull up very steeply to convert some of the kinetic energy into potential energy. He only spends about 4-5 seconds at the crazy steep angle.

For zooming at these speeds, the mass is not very relevant: it appears in both kinetic and potential energy terms and cancels out.

$$\frac{1}{2}\cdot m \cdot \Delta V^2 = m \cdot g \cdot \Delta h \Rightarrow \Delta h = \frac{\Delta V^2}{2 \cdot g} $$

He just needs to take a longer take-off run at higher take-off weight to reach the same speed.