Signposting

Small navigational sentences do the work here. "That is the first of three, and here is the one that surprised me" gives a viewer a reason to stay through a transition, and stops a video feeling like a list of unconnected parts. Overdone, the same lines become throat-clearing. A sentence announcing what you are about to say instead of saying it costs you attention, so signpost at the joins between sections and leave the rest of the script alone.