I m from Argentina and this news is great !! I m veryy happy and I don't know why they choose that day, but is a wonderful new !! =)
I think that it is because in Buenos Aires the films changes only in thursdays.
Quote:
Originally Posted by
EmmaRiddle 
An online rumour stated that
Half-Blood Prince would be released in Argentina on November 19th of this year. Warner Brothers have now confirmed that the film will be released in that country on November 20th.
Half-Blood Prince will in the U.K. and U.S. on November 21st. It
opens on December 11th in Australia.
Source:
UHP