Jemma is Dan's wife who often appears in his videos. She also has her own channel although it isn't as famous as Dan's. A friend of their's, Leah, is also a YouTuber. Link below. She appeared in the video HAMSTERS! as a person to race Dan in The Great Hamster Race.
In The Sorcerer's Stone, Harry walks with his white owl, Hedwig, through a snowy cloister courtyard located in Durham Cathedral. Harry first learns to fly a broomstick on the green grass of Hogwarts' school grounds, filmed inside the walls of Alnwick Castle, located 30 miles from Newcastle.
Oh, and as you'd expect at Hogwarts Castle there are plenty of obstacles such as trapdoors, coloured carpets, prefects and of course suits of armour. Keep an eye on your identification reading at the bottom of the screen.