So Tobi being able to watch what Zetsu recorded is due to their mental connection. Similar to a kage bunshin knowledge transfer.
And Kakashi obtained the MS because he killed Rin. Who would have thought
It also explains Kakashi's personality a bit, i think he lost motivation because of these events that happened to him and that's why he didn't really become a kage level guy. Instead of facing the real world he escaped into Jiraiya's imaginary world by reading the books even when working. It was probably Naruto who gave him back his motivation to be a better ninja, because until he meets with Naruto he didn't progress at all, then in the timeskip he suddenly obtained MS, it does seem like his motivation to become stronger is to protect Naruto.