Sadly it is totally unrealistic and purely for certification purposes.
There were no:
1) People over the age of about 40.
2) Immobile people
3) Any bags anywhere blocking anything
4) People were all doing exactly as told (no trying to take hand luggage etc)
5) No wind/rain anything that would affect the slides useability.
I am sure other people will spot how highly planned it was!
I wonder if Boeing do it any differently?