Illusie mentions tape recordings of Grothendieck explaining his trace formula and more. Are they or similar recordings online? I guess, even if (what I doubt) everything he thought about that is somewhere in print, it would give an interesting insight in his way of thinking.
Online Resources – Are There Any Recordings of Grothendieck?
ag.algebraic-geometrymanuscriptonline-resourcessoft-question
Best Answer
Illusie told me last year that these tapes of his meetings with Grothendieck are somewhere in his basement where they're very hard to find, so they're certainly not online.
The recording of Illusie's reminisces of Grothendieck to which both posts link has been transcribed here. Drinfeld and Illusie will be releasing a more polished version at some point next year.