Three consonants carry one idea: a thin strip. The oldest sense is to scratch a line; from that line comes the ribbon, the tape, and the film, which is literally a strip of celluloid. Modern Hebrew then builds the whole cinema vocabulary on it: the act of filming, the camera, the script, the screenwriter, and the short clip you watch on your phone. The crab and the zodiac sign Cancer share the form too, by a separate path. Every word here is verified against pealim, niqqud included.
The same root runs through the verb system. Each binyan is a voice: it bends the one idea into active, passive, causative or reciprocal. Tap to hear.
The two verbs split the root cleanly: the old pa'al לִסְרֹט keeps the literal "scratch a line", while the modern hif'il לְהַסְרִיט means "to film", to commit something to the strip. Its action-noun הַסְרָטָה (filming) appears below.
Same root letters, different noun moulds (mishkalim). The mould tells you the function: who does it, the act of doing it, or the thing produced.
Strip the prefixes, suffixes and vowels. Three consonants remain, and the meaning lives there.