The Common room break in starts at scene 87, I think from reading it you can see why it was cut, they tried to make it a hero moment for harry, and includes crookshanks chasing scabbers out of the room. It could work if edited down a bit, I have been working on an extended version for a while now and I know how to bridge the gap left by these missing scenes but I haven't yet got the energy to create the new scenes from scratch, I think I'll wait and see if they do run an extended version and what is and isn't included.
I know that there is no reason to trust this script to be genuine, but I believe it is since it contains the deleted scenes and some other differences to what made it to the final film where as the other Harry Potter scripts on the site are just transcripts of the theatrical version of the film.