Probably because Treyarch + Activision don't want spoilers and stuff to be revealed before they officially reveal them. Oh yeah, and because they don't want to spoil one of the biggest games of the year. Don't forget that 98% of the people who actually post the videos probably don't have the game but they just pirated it.
oh..for me assassins creed brotherhood would be the biggest game of year..black ops is second. just sharing my opinions
It's just that they don't want videos posted yet, period. Even people at Machinima who were sent early copies had their video posting abilities severely limited and were forced to remove or make completely private all Black Ops videos after a certain time period. That, and it's a good way to catch pirates. Chances are that if you are just a random person posting your game play footage, you pirated it, are going to be reported to Microsoft, and will be at the very least severely warned on youtube.
prototypes my all time favorite game assassins creed brotherhood is my most anticipated to me basically but its big.
Does it matter to spoil something coming out in like 6 days?Unless it is the ending of the solo campain.
Yes. It's still a business Solar, and the thought of someone not buying the game due to a spoiler, equals money they do not make off the game's revenue. They will protect their IP to no ends.