I tried to watch this a while ago but like you thought she was glazing over a lot of detail. I stopped watching it after 20 minutes or so.
She picked out the salient points: the murder weapon being left on the settle and not locked away, Neville would telephone police himself if injured, not leave it to a proxy, Sheila's appearance made it unlikely she was involved in a fight with her father, Jeremy embellished a story about Nicholas and Daniel being taken away from their mother, when it was Colin who had charge anyway.
Robin was supposed to be wearing gloves when there was no point if he were bent on suicide, the ridiculous typewritten part-ungrammatical sentence left on the computer, when it was Arawa who was the star of the family, the marks on David's person in contrast to the tiny scratch on Robin.