Why isn't Katy Perry in the Flo Rida Video "Right Round"?

I KNOW she is featured in the song, but just wondered why she isn't in the video? And I've heard ppl say it's Kesha, but I've seen soooo many titles of the song, even on yahoo music videos that say "featuring Katy Perry". Her voice is pretty unique, I'm 99.9% sure it's her, so I thought for sure she'd be in his video, but when I finally saw it - no Katy Perry :( ... So my question's just basically why she is not in his video (if anyone knows) or am I wrong & all the song titles I've seen are wrong & there is someone else that just sounds exactly like Katy Perry, lol? ... Thanks