The video predicts many future benefits the day when optical computing becomes practical. They don't say they have a working computer. The project is still in research and development.
The concept of optical computing has advantages:
* Needs no wires. So needs no current return path.
* Generates minimal heat. Wastes minimal power.
* Not hindered by internal parasitic capacitance.
* Not hindered by external magnetic flux fields.
As for the hardware, I imagine a chamber where at one end is a narrow-beam 'write gun' and narrow-beam 'read camera'. The other end has wall of memory cells, made of a luminescent substance, arranged in a grid. The 'write gun' lights up a cell by shooting it with a certain color, or makes it go dark with a different color. The 'read camera' senses whether a cell is bright or dark. I have not heard this exists yet. It's just a conceptual picture.