I just read up on Valeera Sanguinar, and yes, she's a friend of Varian, but I'm not sure you can class her as Alliance completely. She seems to be used as a rather neutral character with definite Blood Elf things going on, but also being present on the Alliance side in Battle for Undercity for instance. I think she's on Varian's side, through friendship, but not necessarily in a political sense. She urged people to work with the Horde in Wrath for instance.
I guess she'd probably make a good choice to do the Forge video they said they'd make, if they continue with the Horde vs Alliance themed fights. She'd just be the joker and get used for that in stead.