The parade lasts for over 2 hours. They rehearse for 5-6 weeks before the birthday parade. These soldiers are real combat trained soldiers. Who take time out of their normal military training to do ceremonial duties in London for 6 months then return to normal soldiers training/ duties.
It takes place on the 2nd Saturday of June every year. This year it will be the Kings Birthday Parade, Trooping the Colour. The blue you mention is the St.Patricks blue plume of the Irish Guards. Welsh Guards is white green white. Coldstream Guards is red. Grenadier Guards is white, and the Scots Guards who are Trooping on this video don't have a plume in their bearskin
You wondered why there are different colour plumes on the bearskin caps. They indicate to which of the 5 infantry regiments of the household division they belong. White for Grenadiers. (buttons on tunics in singles) Red for Coldstream Guards (buttons in 2s) Scots Guards no plume (buttons in 3s) Blue for Irish Guards (buttons in 4s) Green and white for Welsh Guards. (buttons in 5s)
Yes the Colour is the flag of sorts. It is the colour that shows soldiers where their regiment is when in the middle of the battlefield. It also lists their battles. No it is not Buckingham Palace. It is Horse Guards Parage ground. The metal chin strap is there to protect him for his enemies swords etc. Also, with such a high hat, it makes it easy to lose the hat in battle without pulling harshly on the neck and hurting the soldier even more.
The chain on the hats sits where it does (rather than under the chin) because it was too deflect a glancing sword blow in the days when soldiers mainly fought with blades. The hats themselves are bearskins, a battle honour, originally taken from dead French soldiers during Napoleonic times.
The reason the bearskins chain is not under their chin is because if it was to be shot or knocked off their heads in combat it would snap their necks so they moved the chain under their mouth
I realise that this is an idea about training the army, but in the British Army they would be useless as soldiers if their brains did not work. The men are working soldiers and fight for their country, but they have so many months on duty and so many months doing ceremonial duties. It gives them a break from the battlefield and its horrors. Though the Sergeant Major yelling at you because your boots are not shiny enough before going on parade may be horrifying in a different way too.
When they join the army basic training includes marching on parade like this and if they can't pass a certain standard in marching then they are not allowed to join the house hold divisions and would instead join other parts of the army where marching like this is less important.
That's a very silly comment to make. These are first class infantry soldiers performing a ceremonial parade that has it's origin in the reign of King Charles II.