The article mentions a maximum of 8 watts. USB power is measured in "Unit loads" (100ma in 2.0, 150ma in 3.0) up to a maximum of 5 loads in 2.0 (6 in 3.0). Reaching a total power of 500ma in USB 2.0 or 900ma in USB 3.0 as a standard. Provisions have been made for high-current devices, where the USB 2.0 port can provide 1500ma in a charging situation while still acting as a data port, or 1800ma in a power-only mode (where voltage is allowed to go up to 5.25v). Note that both devices have to be high-power certified to raise current levels that high.
So the total maximum power you could expect from a modern USB 2.0 port, would be:
5.0v x 500ma = 2500mw original specification.
5.0v x 1500ma = 7500mw Modern, while still transferring data.
5.25v x 1800 = 9450mw Modern, high current charging only (no data).
Either way, that puts the monitor right at the dangerous threshold of current draw, and you can bet that it wouldn't work in older USB ports that only deliver 500ma.