I'm sorry that in your opinion the school is in such a bad state and you feel as though you are all being ignored.
I have watched the You Tube video and wasn't hugely shocked to be honest. I have been and visited worse schools, some of which were located in buildings erected well over 100 years ago.
I work in a school that was built to accommodate 400 pupils back in the 1950's. The school has expanded and currently has 1000 pupils. We have over the years been granted plenty of port-a-cabin classrooms, some not in the greatest state of repair, but as and when the school started to look shabby and with no budget to do anything really grand we have turned to our parents and the PTA.
We have achieved very reasonable results, a lick of paint, anti fungal paint is very good for areas with mould, toilets are especially prone to this, your school is not alone here I'm afraid. Parents and the PTA donated benches, toys, flowers for the outside areas and many parents gave a lot of their spare time to the school to help improve it.
Sadly as for the prison style/bar fencing.... this is a result of our modern society we live in. We have these at our school too, with very sharp razor points at the top. The sole intention of keeping out would be thieves, vandals etc. Our entire site is fenced in like this, its a sorry state to be in, It does also help to deter anyone else getting onto the school site during the working day, After school tragedies such as that which occurred in Dunblane, Schools have to be extra vigilant.
I do find it slightly offensive to compare your school to a third world school. The education your children receive in the school is in no way comparable to that which is taught in third world countries. At present our school is raising money through collecting pennies to help build a school in an area of Africa where at present the school community meets for lessons under an Acacia tree!!
Please be realistic!
To make more of a stand and produce a more professional argument to those in charge of the pennies, I would suggest, changing your You Tube video by firstly checking all spellings and removing the sarcastic comments such as when the toilet is on show not having the best place to contract a urinary disease (or whatever the exact words are) displayed. Its joking and in bad taste and those in the higher office wont like it, make a proper video, showing, statistics, number of complaints, number of hours children are taught in the hall etc.
Best of luck and hopefully you will get somewhere and if not... rope in some of these parents, form a group and start cleaning/painting!