I had wondered how this individual was going to make Inkjet printer ink out of highlighter pens. I mean, considering the ink is priced somewhere around the same rate as liquid gold, I figured it was either going to end up being "way too easy" or we'd find out there was some important reason ink was so expensive. Neither was the result -- that's a Dot Matrix printer. I'd imagine if I'd have turned the volume on, you'd…
They work on the same principle as typewriters did, which also used a ribbon. (https://en.wikipedia.org/wiki/Typewriter_ribbon)
The reason they're called "dot matrix" was to distinguish them from another contemporary type of printer that had type (letterforms) built directly into a ball or wheel, so that instead of an array of pins, a raised metal piece in the shape of (say) an "A" would strike the ribbon. ("Daisy wheel" printers were of this type.) These had nicer-looking, non-pixellated type, but they were slow and couldn't do any graphics.
So if this really were a dot-matrix printer, she would have been putting highlighter ink onto a ribbon, but she was putting ink into a reservoir.