Warcraft Lore 6: Grom Hellscream's Redemption

Grom Hellscream and his clan had rallied with the up-and-coming chieftain Thrall in the battles to free themselves from the humans and in the journey to Kalimdor. Mannoroth, the demon Pit Lord and master of the Fel Orcs, wanted to curse Grom and his clan again with his demon blood to make them Fel Orc savages once more under his command.

However, Thrall was able to get to Grom in time to purge the demon blood once again and to cleanse him, but Mannoroth would not give up his orc servants so easily.

Mannoroth, had started to work his fell magic again on him and his clan. This time, Grom would not fall again under the curse, no matter the cost..

Warcraft Lore 5: Archimonde Destroys Dalaran

As Thrall continues to rally the Horde and Tauren in Kalimdor, Arthas and Kel'Thuzad summon Archimonde to Lordearon.

This powerful demon is an Overlord of the Burning Legion and uses his powerful magic to destroy Dalaran, city of the Kirin Tor. This is a step closer for the undead Scourge and Burning Legion to conquer all of Azeroth

Warcraft Lore 4: Arthas' Betrayal

Arthas, prince of Lordaeron, was turned from a ...
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Added: March 28, 2007
Arthas, prince of Lordaeron, was turned from a young paladin to the "dark side" and became a Death Knight by the power of the runeblade "Frostmourne" which he was tricked into obtaining by the Lich King.

Here shows his homecoming after defeating The Scourge undead armies in Northrend; but he has his own agenda....

Warcraft Lore 3: Medivh, The Prophet's Warning to Lordaeron

After Thrall started rallying the Horde and fre...
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Added: March 28, 2007
After Thrall started rallying the Horde and freeing Orc captives and when The Scourge was starting to invade the human lands of Lordaeron in northern Azeroth with a plague, the prophet Medivh, The Last Guardian, appeared to warn all humans who would hearken to his message to make ready and take up arms agains this new, alien threat, not the Orcs. Sadly and fatefully, Terennas, the King of Lordaeron and father of Arthas, did not listen.
However, Arthas and his knights would take up the battle against the plague and find the enemy behind it

Warcraft Lore 2: Medivh Speaks to Thrall in a Dream.

Medivh, The Prophet and Last Guardian, warns a ... (more)
Added: March 28, 2007
Medivh, The Prophet and Last Guardian, warns a young Thrall about the coming invasion by The Burning Legion in this dream/vision

Warcraft Lore 1: Coming of the Burning Legion and Scourge

This is the first in a mini series of CG movies from Blizzard Entertainment's Warcraft Series that describe a bit more of the history behind World of Warcraft.

This movie came with the WC2 CD as a preview trailer. This story is about 4 years before WoW.

Story: The Second War, by human reckoning, was over. However the strife between orc and man continued. Only a new, otherworldly demonic threat may bring the warring races of Azeroth together, perhaps. The Burning Legion makes their appearance in Azeroth and bring with them a plague that will turn all into undead slaves; thus The Scourge is born

Fury of the Sunwell

The glorious fount of arcane energy known as the Sunwell empowered the high elves for millennia, until the death knight Arthas laid siege to the elven kingdom and corrupted its sacred energies. Seeing no other alternative, a band of survivors led by Prince Kael'thas destroyed the ancient fount, and over time the surviving elves fell prey to a crippling magical withdrawal. Now, promising salvation for his people, Kael'thas has returned. Soon the Sunwell will shine once again, but whether the sacred fount will usher in deliverance or destruction remains to be seen. This area includes: * A new quest hub * Magisters' Terrace - a 5-player instance * Sunwell Plateau - a 25-player instance * New badge rewards New Daily Quests: The combined forces of Shattrath have launched an attack on the Isle of Quel'Danas to confront Kael'thas and the Legion at the Sunwell and surrounding areas. Players will now be able to gain reputation with the Shattered Sun Offensive and participate in a new set of daily quests. UI Improvements: The combat log has undergone improvements that allow more robust combat-text filtering, including the ability to define custom colors for enemies and friends, as well as combat text filtering for self and others. Arena Tournament Introduced: Players will be able to create level-70 characters with epic equipment and compete on special tournament realms in a new global arena tournament. For more information, details, and entry requirements, please visit the official tournament pages.

And more - check out the full patch notes.
http://worldofwarcraft.com/patchnotes/