I recall reading on the liner notes for the Mark Twain Tonight LP that
Hal Holbrook used both rare film footage to study his manner and gramophone
recordings to study his voice. They exist somewhere.
Achtung: Here Richard H. Cracroft raises his (wizened) head: I use
the film," Mark Twain Gives an Interview" (1961, Color, 16MM; 14
min.) whenever I teach Twain. Important to an otherwise excellent Hal
Holbrook "interview" with high school students in the Connecticut
home and pool room, is the thirty-second original clip of Twain at
the home. It is the only place I have found it available and
treasure it. I suppose that your campus audio-visual centers can get
this; it's probably on video now.
Richard H. Cracroft
Brigham Young University