It seems like only within the last year I've noticed this usage, as a verb to view various parts of a digital resource. Dictionary.com does not have any definition for scrub that is similar to the verb form of scroll to view various parts of a digital resource.
[A paraphrased tooltip on YouTube on mobile]
Swipe upward for fine-scrubbing
[In technical documentation for a video sequencer editor]
Scrub to the end of the sequence . . .