It was something about his father being a wizard and left when he realised that Dean's mum was pregnant i think. That's the thing i would only do it if JK approved and i would only do that storyline if JK allowed it to be put in one of the early series. Perhaps series 2 or 3. EDIT: Just checked JK's site for it and it was in CoS, which would be kinda perfect!
My plan would be to make Hogwarts feel more like home and to have the other characters in Harry's year more involved so that it wasn't just him, ron and hermione but we had some other "regulars".
I watched a bit but i couldn't really get into it.
EDIT: yes, i forgot he ran off because of DE's chasing him. Trying to protect his family.
I could try and put in the scene between Malfoy and Nott that JK had originally put in. I might put more Malfoy in and Nott because i do think they are interesting characters and want to know more about them but in the pilot of course, i won't need them but perhaps when i adapt the full book perhaps i could feature them more.