Landing on the right frame
The moment you want is often one or two frames away from where a scrub lands, and in fast motion those frames differ a great deal — a blink, a half-formed expression, a hand in the wrong place. Step frame by frame around your target rather than accepting the first pause. Motion blur is the other constraint: it is baked into the recording, so a frame from a fast pan will be soft no matter which one you pick. Choosing a moment when the subject is briefly still is the only real remedy.