Because you can quickly verify that the rumour about James Jebbia being a child actor who was in Grange Hill in the 70s is, in fact, true, even if you don't own the first series on dvd.
3:19 - 3:37 is the best glimpse of Double J as Tommy Watson.
For whatever reason Jebbia only lasted the first series before he was replaced by another actor called Paul McCarthy as the face of Tommy Watson. McCarthy then went on to have a long thespian career with post-Grange Hill roles in Tucker's Luck in 1981 and, erm, an episode of The Bill in 2004.
Some people have scoffed about a British kid actor like Jebbia going on to run the ultimate NYC street brand but they done got shit all twisted because it makes perfect sense when you think about it : from Tucker and Benny to A-Ron and Harold.
I dunno what's on BBC2 sunday mornings nowadays, but if they start showing Grange Hill repeats from the very beginning again then I'm there with the swiftness.