It was largely correct, but made a few errors, Kael’thas was not in charge of Quel’thalas when the Scourge invaded, that was his father, Anasterian, whose death, along with 90% of the people, was what -prompted- Kael’thas to rename his people Blood Elves.
Quel’thalas was not part of the Alliance in WC3. Kael’thas led some volunteers (Largely those blood elves who lived in Dalaran) to aid humans, and fell under the command of Alf Garnett…Ahem, sorry, Othmar Garithos… Quel’thalas itself was neutral during WC3, much like Strom and Gilneas.
(Interestingly the video does show the dialogue which means the humans were quite alongside Garithos’ orders. Guess this means that next time someone blames ‘The Horde’ for Sylvanas, we can blame ‘the Humans for being racists’ 
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Oh undoubtedly, he was the Aedelas Blackmoore for the next generation, he was the exception to the rule, that humans are tolerant. He was however the exception who had the biggest army in the area. Stormwind was neither the dominant power in the Alliance of Lordaeron, nor geographically positioned to do anything about it.
Definitely not. They are as different as the Dark Horde who came through the Dark Portal are from the Horde Council, for the same reasons, attitudes and leaders changed. For a start, in the WC games it was not the current Alliance, it was the Alliance of Lordaeron, whereas now in game it is the Grand Alliance. Two very different body politics with different aims Both Horde and Alliance have changed massively in terms of how they operate.
I think that was a Garithos thing. Remember, at the end of WC2 King Terenas II was the one who wanted to put the Orcs into Camps, whereas Arathor, Gilneas and Quel’thalas were just like “No, we’re not paying for that, just kill them all!”
Terenas at least seems to have been tolerant.
Think of it as an Elven thing. Because it is. It was nothing to do with the Horde Exiling them, the Horde probably didn’t care. The Sin’dorei however did care, and that is how Elves deal with their problems, Exile rather than Execution.
Night Elves did not like the Highborne practicing Arcane, but rather than Executing them, they Exiled them under Dath’remar Sunstrider.
They then became the Quel’dorei.
Scourge invaded and almost everyone died, the race renamed itself as Sin’dorei.
The technique of draining mana from living creatures is taught, some Sin’dorei really don’t like that, and rather than Executing them, Lor’themar Exiles them. They then call themselves Quel’dorei again, and seek refuge with the Alliance.
Later still, a bunch of people study works of the greatest Traitor to Elvenkind , and instead of Executing them, Lor’themar Exiles them, they then name themselves Ren’dorei.
Exile seems to be the Elven ‘Go to’ response, rather than Execution (Possibly why Garithos’s planned actions caused such horror and revulsion?)
