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.
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.
Will we continue Scientific Research http://cds.cern.ch/record/912518?ln=en Allons nous continuer la Recherche Scientifique Recording number CERN-AUDIO-1972-003 Speaker(s) Grothendieck,A Date 27 January 1972 Duration 138 minutes Language French Keywords Science Synopsis Réflexions sur la science- responsabilité du savant Copyright © 1972 CERN Notes partie 1: exposé partie 2: questions f/a partie 3: questions f/a Listen to Part 1: Part 2: Part 3:
100 hours of audio of lectures of Grothendieck http://www.archmathsci.org/catalogue/general-chronology-of-recordings-since-1973/chronology-of-recordings-1973-1980/1973-recordings/ 1973 Recordings Lecture Courses by Alexandre GROTHENDIECK 3 Lecture Courses on respectively 1. Algebraic Geometry 2. The Theory of Algebraic Groups 3. Topos Theory
The copyright of all these recordings is that of the Department of Mathematics of SUNY at Buffalо.
There is a recording of Illusie talking about Grothendieck at The Grothendieck circle. I couldn't find any recordings of Grothendieck himself.