People have not seen the Emma Watson porn, and those that have can probably read the word deepfake in the title. My guess is between 5% and 20% of the people who have seen it, and found it through searching for Emma Watson, rather than Emma Watson Deepfake believe that they have seen actual Emma Watson in porn.
But ultimately, you said that you didn't believe that it was irresponsible to assert that deepfakes will society more skeptical of video. That is your claim. I pose that deepfakes can easily be used to produce videos which are closer to what their audiences expect than reality, and as a result they will likely be less suspicious of what they see.