Who is this actress and what is the video?

I keep seeing this video on youtube in meme formats, but I'm never able to actually find the original video. It's annoyed me so much that I've decided to finally come and deep search for it, so if anyone could help me find it, that'd be cool. I don't know any of the actors or actresses, I don't know jack shit about this video other than this part of it for the meme formats.