Here are two posts I wrote for the blog of Oxford University Press, both concern ineffable facts and the possibility of deep ignorance. It’s all explained in the posts:
Ineffable facts, deep ignorance, and the sub-algebra hypothesis: Part 1
Ineffable facts, deep ignorance, and the sub-algebra hypothesis: Part 2
And here are two videos from the annual Philosophy in 15 Minutes event, hosted by the UNC philosophy department. Only 15 minutes each!