I've long wondered why they don't do this for video ads. If they were served as part of the main video stream it would be almost impossible for ad-blockers to filter them.
(I even think the DASH segmentation would allow them to this without reencoding the original video, but that's just speculation on my part)
(I even think the DASH segmentation would allow them to this without reencoding the original video, but that's just speculation on my part)