Why does FFMPeg sit at 00:00:00.00 if I start cutting a video a long ways into the file?
-ss after the input name performs a slow seek where ffmpeg decodes all frames but discards till it reaches the seek point.

With -ss before -i, ffmpeg performs a fast seek.

FFMPEG.exe -ss hh:mm:ss -i in.webm -q:a 0 -map a -t hh:mm:ss -y out.mp3


But you'll have to specify a duration instead of to with most formats.