>>"How? If your method of identification is dropped frames and I drop more frames then you can only see the total dropped frames, not the number of frames I dropped thus"
Because I have the master list of which frames I have dropped for each recipient and can add back in any you have dropped which aren't on the list. Unless you magically coincide with the same frames by happy accident (and you have to win that lottery multiple times to really obscure the signature) then I can tell the difference between which frames you have dropped and which ones I have dropped.
Now obviously if you had access to all or many different leaked copies you could do comparisons and work out which frames I had dropped from each of them and then remove all such frames from a single copy thus anonymising it, or put ones back in making it look like it's from another. But you can only do this between sources you have copies from which returns us to the situation where you have to have compromised many recipients rather than a small number or one.
Basically, if you have only compromised one recipient, what you suggest cannot work. If you have compromised two recipients then what you suggest can obscure whether your copy originated from either of those but it doesn't help you because my inability to distinguish which one out of two gives me the same information - I know that these two recipients leaked. Your technique basically only works to obscure videos between leaked parties by which point I already have the information I want.