My DS (7) had this just last week, there was only 1 person, a SALT, and she had me sitting behind DS with them both at a small table.
She did record everything with a camcorder and was careful to make sure DS was firmly in view at all times (chore in itself as he sometimes insisted on sitting on the floor
) and asked me to stay as in the background as much as possible.
It's very relaxed, she asked some questions between play based activities, I was totally confused by some of them, she asked him if he would like to be married, what he might like about being married or dislike about it, but explained at the end she was looking for his ability too imagine future social situations (DS answered all 3 with 'I don't know').
She also looked for things like eye contact, his ability to play WITH her, make up his own stories, his feelings etc. I will say that it's not very obvious what they are looking for when they do certain activities (at least for me, but I can be a bit dense
) I thought DS was doing very well with some things until she explained at the end why she did them and I realised that actually he hadn't been doing aswell as I had thought.
Bit long winded but hope this helps, It is only my own experience but feel free to ask any questions if you like and goof luck 