And if they’re not, the client can download the video twice and diff the copies.
The most pernicious thing they could do is randomize the ads across users, but serve each user the same ads each time. In that case, you’d need a peer-to-peer client to compare hashes of chunks with other users to detect the ad segments.
If they’re predictable with the timing and length then sponsorblock will still work.
And if they’re not, the client can download the video twice and diff the copies.
The most pernicious thing they could do is randomize the ads across users, but serve each user the same ads each time. In that case, you’d need a peer-to-peer client to compare hashes of chunks with other users to detect the ad segments.