Blurring just leaks information unnecessarily. We should go beyond blurring. In fact we could go beyond blacking out with bounding boxes too; we could use some kind of Mask CNN to segment the boundaries of people's silhouette, and then black those out.
This is what I would imagine it would need to look like:
[video input] -> [frames]
per frame:
[frame] -> run thru a person detection segmentation nn -> output an outline mask for the frame
fill in the outline mask in the frame with eg. black
reconstitute [set of frames] -> [output video]
