How do I get the 'Filepath' attribute from a sound strip in the VSE? How do I get the filepath attribute from a sound strip of a video sequence ? I am talking about the sound strip that comes with a video file.

Sound strip : demo.001   bpy.data.scenes['Scene'].sequence_editor.sequences_all["demo.001"].filepath

==> 'SoundSequence' object has no attribute 'filepath'

I can get the filepath from the associated video strip.

Video strip : demo.avi   bpy.data.scenes['Scene'].sequence_editor.sequences_all["demo.avi"].filepath

==> this works
You need to access the sound property of that strip which has the filepath property: 

bpy.data.scenes['Scene'].sequence_editor.sequences_all["demo.001"].sound.filepath