I don't know about "zero" impact.
We got held up a few minutes between a few sessions while the crew van ferried a camera crew on and off the track. The film crew themselves were not intrusive at all. They were out there over different sessions at different corners but I hardly noticed them.
The Hot Laps riders were responsible for two of the crashes on Sunday. Not that they were anything special, there were a lot of incidents on Sunday. I think that Volkswagen made more laps than I did. There was not a single incident Monday, but then, the Hot Laps guys had only one bike running on Monday.
I was surprised at how unprepared the Hot Laps team was for track days. Besides the crashes and the bad gas. Their bikes just weren't prepared as track bikes; license plate, taped lights, 10 year old bike that had never had fork service, none had ever had basic suspension set-up done. By the end of the weekend Johns Sherrard & Bickle had moved them a quantum leap forward.
5 people showed up to compete in Hot Laps, 5 more were drawn at random from people at the track wishing to try.
I left before the final timing session, so I don't know how it worked out in the end. (there was a significant delay for an incident Tuesday morning, only one morning session for Yellow & Green)