One distinction between Lisp and Python's docstrings that he didn't mention is that in Lisp, you can (and it's normal to) give docstrings to variables; you can then look these up later with DOCUMENTATION or however else you read docstrings:

    CL-USER> (documentation '*print-readably* 'variable)
    "If true, all objects will be printed readably. If readable printing
      is impossible, an error will be signalled. This overrides the value of
      *PRINT-ESCAPE*."
    CL-USER> (documentation '+ 'variable)
    "the value of the most recent top level READ"
    CL-USER> (defvar *variable* nil "a variable")
    *VARIABLE*
    CL-USER> (documentation '*variable* 'variable)
    "a variable"