https://stackoverflow.com/questions/8877228/opencv-detect-blinking-lights

ffmpeg -i PXL_20220806_231420638.mp4 -filter:v "crop=200:200:725:275" output.mp4

PXL_20220806_231420638.mp4	725x275	200x200
PXL_20220806_231644224.mp4	790x380	200x200

Mon Aug  8 17:24:55 PDT 2022

PXL_20220808_233318199.mp4

captures w/ a delay of 35ms instead of previous 34ms (for 4224.mp4)
also w/ a smaller resistor, 68Ω instead of 100Ω.