Well entirely is hard, but the majority with a few resources it can be done...
I totally remember in my high school a biatch that filmed a guy F* her and "bubble gum" out of a "round hole". She worked at a disco and she lost her phone and someone uploaded on porn sites, it spreaded like a virus...
Their family went on court and the video was removed almost every day from the majority of the most known porn sites and they couldnt upload it anymore in all the known ones... The last time I saw it was compressed on file sharing sites. And she also had 17 back then if I remember well.
If she was 17 then legally it was considered child porn and the video you mentioned would recieve a special level of attention that nothing else would. Despite that you say you still saw it online years later -- so even in this extreme case the removal was entirely successful.
Besides there are people who would take time to preserve something like source code for a popular piece of software, court orders be damned. The same can't be said about some random porn video, especially if it was classified as child porn.
Movie, music & software piracy are still rampant online despite their legal status.
BTW I kept thinking about it but just don't get the bubble gum out of a round hole line....
