I think the events after completing the Besaid Cloister should be included as a moment, perhaps as "Yuna Becomes A Summoner". From, Tidus meeting Lulu and Kimahri, the FMV with Yuna leaving the Chamber of the Fayth, the ceremony with Valefor being summoned, and the campfire at night afterwards.
(From the end of the first video into the start of the second).
Another moment I'm less sure of, but I really like, is when Yuna decides to tell the party she's chosen to marry Seymour (in the Thunder Plains).
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We are living our lives
Abound with so much information