Helen's a well-known actress
Shaun's a well-known actor
Derek's relatively well-known
Sarah's from the biggest girlband of the past 15 years
Sandi's from a very popular TV show
Amelia finished 3rd on the X Factor and had a couple of Top 40 hits
Paul was famous...a while ago
The "why are they famous?" ones really are Sam, Karthik, Chad, Jordan, Jemma, Marissa, Brandi and Trisha. But then YouTube has bigger outreach than most other platforms today so I wouldn't consider Trisha in that bracket.