Automating QC to find corrupt video files
Since QCTools wraps the ffmpeg/ffprobe and uses the signalstats filter, here is how to achieve what I wanted:

ffprobe -f lavfi movie="Bad.mp4","signalstats=tout" -read_intervals %00:01 -show_frames


-show_frames outputs the frame summary into STDOUT. It contains the value that I need: 


  TAG:lavfi.signalstats.TOUT=0


-read_intervals allows me to process only a small part of the file to get signal stats from only a small portion of the file

We can also check how QCTools does it by looking at the source code here:
https://github.com/bavc/qctools/blob/master/Source/GUI/BigDisplay.cpp#L844-L845