I've got a lot of favorite video parts from Natas Streets On Fire to Public Domain Rubber Boys, Ban This Barbee, Ed in 1281 to Lotti in Now n Later to Stranger Skypager to Jason Adams Label Kills to Cardiel Sight Unseen to Drehobl Free Your Mind to Arto Sorry to Grant Mind Field etc. and a lot of them for different reasons.
But if I had to choose one that's the absolute best representation of skateboarding in film, it's Gonz in Video Days.
Second I'd say Tent City as a whole.