He's discussing history; it's not an apologetics lecture, and not a devotional or Bible study.
Solo Scripture means that God can not change. If He does speak to you, He WILL NOT say anything different than what He has written in the Bible (spelling?)
It's sola scriptura. But you don't need sola scriptura to get where you're going; all you need is a belief in the inspiration of Scripture, an orthodox belief about the nature of God, and logic.
Hasn't the "Word" changed over history?
I understand, but he is speaking with no footnotes for his claims, that's all.