I searched for a FFmpeg command to blur part of a video, and found the following:
ffmpeg -i short.mp4 -filter_complex "[0:v]split=2[v0][v1]; [v0]crop=200:200:60:30,boxblur=10[fg]; [v1][fg]overlay=60:30[v]" -map "[v]" -map 0:a -c:v libx264 -c:a copy -movflags +faststart filtered.mp4
Unfortunately, I can't blur the part of the video that I want to blur. So, I took a picture with the same resolution and color so that someone may help me understand what to do, and perhaps even explain what the numbers in the code above mean or refer to.
Here's the picture: