I think its a good place in the history of WoW to attempt this.
We will spend 1 week in the nominating process (or until posting in this thread dies down). After which, I will set up a bracket to vote for videos. I don't think a video has to have millions of hits to be considered great, and some of these are very old now.
I will open with some of the more famous ones:
1. Unbreakable PVP
Claim to fame: Demonstrated the absolutely domination of the enhancement shaman in vanilla WoW PvP. The OPness was so ridiculous, that Blizzard nerfed enhancement shaman until the end of time...
2. Serenity Now VS Winterspring Funeral
Claim to fame: Either hilarious or twisted depending on your disposition. Excellent choices of music, well put together, emotional.
3. Leroy Jenkins
Claim to fame: Actually crossed over into mainstream culture to some degree because of how hilarious it was. An in-game title created in its honor.
4. Blind: Hide and Seek - Blood elf rogue invades Stormwind
Ground-breaking in its time. Used the in-game animations amazingly well.
5. Betty and Me
Johnathan Coulton had some hilarious songs, and I thought this was the best of his WoW videos set to his songs. Either this or Re: your Brains.