That's basically the CPU running at 1.024 Mhz. The video hardware is dumb, runs independent of the CPU, and just scans a region of memory to send pixels to the display. All software pushing pixels otherwise.
You are not wrong with the NES, C64 and other machines using a graphics chip with sprites and other hardware features to assist in various ways. But, quite a lot happened on the CPU.
BTW, this game is done on a 1Mhz 6809, all software pushing pixels.
(I would skip out to the middle somewhere in that video to get a sense of what is being done)
On that game specifically, it's a single frame buffer. Screen divided into two halves, each drawn while the display is delivering the other to the player.
The Fujitsu FM-7 line of 8-bit computers actually shipped with two 6809 compatible CPUs (Hitachi 6309 IIRC) and the second one just did software graphics the whole time pretending really hard to be a GPU.
