If you are going to talk about the ending of a film (or indeed the details of any film) it is common courtesy to those that have not seen it to have a subject line of
No Country for Old Men - SPOILER.
Then add a bit of text at the top so your comments about the film are pushed down the page for those that dont want to read it.
This is a new film that many people have not seen and I think you are being very rude and thoughtless to put the text that you have.
I totally disagree - anyone thinking of going to see any movie will have read at least one review -and every review of the film that I have read states the ending is 'disappointing'. Therefore IMHO there was no need for the word Spoiler as this does not come as a surprise to anyone.....I did not disclose what the ending was - if I did then yes, the word spoiler would have been needed.