Refers to an "in-depth" and through "exploration" of the transcript from a lengthy/boring/complicated speech. lecture, etc.
In an old late-'80's political-satire cartoon , John Tower is shown being sentenced for his alleged political improprieties; the "stiff penalty" that the judge imposes on Mr. Tower is spielunking the entire many-hundreds-of-pages-long Iran-Contra-affair investigation-report --- "May you die of boredom, Mr. Tower!"
by QuacksO May 14, 2019