ok.
Around 40 minutes of them asking you questions about her behaviour, mobility and so forth. A lot will to about what she does during the day. Eg, round here, a classic question would be whether you take her shopping-from your answer they would judge whether she could walk, what her concentration was like, etc etc. They will ask you questions like this for about 40 minutes to an hour, then you will be asked to wait outside for 10 minutes or so, while they decide. Very rarely they cannot decide that day, but normally you will get an answer same day.
Misdee, I'm sorry, it is gruelling and horrible IMO. Having said that, with the right panel it can be not too bad, and it depends on the case.
Your best bet is to a. know the criteria for DLA well, and think how your dd's condition relates to it b. don't lie, or if you do
be very very convincing. The chair is a lawyer, there will also be a doctor and a disability "expert" there, and any scent of a lie and you will lose the complete award, believe me. Its shit but its how it works.
whether to take youe dd with you is tricky. probably not, because if she can sit through a dla hearing (which many adults find hard) they will probably draw some very optomistic conclusions about her needs. depends, though, whats her condition?
They don't have facilities to watch a video as far as I know, but you can submit photos, diaries, letters from others (and take anyone else you want with you) letters from the school, anything really.
Just remember that the rules for DLA are strict and deeply unfair and they have to apply them rigidly, else the DWP can appeal. Oh, you have a right of appeal against the appeal in some limited circumstances also.
Maybe post more about your dd? What condition does she have?