Why? The advertisements could still be added as separate video layers? Sure, they are also easier to be circumvented. But I’d rather supported something like this than end up with real time edited video to insert ads or even worse have “influencers” promote something without ever having really tried it.

If it's a separate layer or different server you can bet that someone will figure out how to remove it from the DOM, hide it, or prevent it from even loading.

Again, I think that's a "feature" a lot of users would prefer to design out.