It does indeed: usually, a raw voltage is passed into a circuit and is then regulated. The raw input voltage may vary a bit, but the task of the regulator is to ensure that it delivers a solid, stable output level.
It may require a raw input level of +5V DC, but then requlate it to +3.3V DC or lower and there many be different voltage level requirements on a given PCB depending on what the design requires.
But yes: it needs a stable, solid 5V DC and enough current in order to supply the components and to ensure normal operation.
A poorly designed USB device may not be able to provide a stable signal and may source less current than it states it can.
Something like this:
The only way to really know is to connect the USB device to test equipment, give it a load and then observe how it performs.
Just buy a decent USB charger that can source at least 2A, 5V DC and try it.
Edit: one replier on the Twitter entry claims that the ACM-V only draws around 700mA or 0.7A - which would be closer to what I'd expect - 2A does seem really a large figure. For example: the MegaCD PSU can source 1.2A but that includes a mechanical CD drive which would require more current as a general rule. Until we get a schematic of the ASM-V it's really just speculation. I would imagine that the actual hardware design itself will be close enough to the standard example circuit in any case, so if someone knows which chip set the thing is based on then get the datasheets and start there to work it out. 2A is a mystery for now.