Sounds Like Fun, but you should be aware that this is an Agency and they will charge you a " registration fee" of up to £60.00 plus V.A.T, and will take commission of a further 15% plus vat, on any fees you earn.
I may be an old Cynic ! but I fear this could be little more than a T.V Add or similar !! I cant help thinking that if someone was contemplating filming a Musical production with a cast of 400 extras and several "well known Film Stars" within the next few weeks we would already have heard something about it via the local press.
'Course I could be wrong .........!!