why do i need to update my surver?

okay so i was on Youtube just a couple phút cách đây and it told me that on march 13th that it was no longer supporting my browser hoặc suver hoặc what ever it đã đưa ý kiến i need to update it with the new firefox hoặc enternet explorer 8...

but why do i hav to do it now?
why not tiếp theo month??