If you are old enough to remember when (5.25") disks replaced cassette tapes as the storage medium for home computing, then the distinction between scan through and scan is clear.
Tape cassettes were (metaphorically) one dimensional devices both mechanically and magnetically. The tape was run backwards and forwards through the reading heads and so you searched through the files stored on it locate the one you wanted.
Spinning a magnetic disk under a head that moved independently opened up the possibility of going directly to a location without passing through every other location between it and the "beginning" of the disk. We talked about random access being far superior to sequential access.
Insofar as a videocassette recorder was analogous to any other magnetic tape, we learned to scan through (probably using fast forward) to locate the section we wanted. On a DVD or hard-drive that is no longer necessary. Menu systems permit you to jump directly to bookmarked positions (typically the beginning of scenes) without going "through" the rest of the movie.
However, I suspect that you intend the software to "watch" the images in sequence in order to extract information. If so, the linearity of the process would make the (seemingly) old-fashioned scan through appropriate.