In order to run Crazyfly python client (CFClient) some prerequisite have to be installed.
# pacman -S python2 python2-pygame python2-pyqt4
Install libusb from AUR
# yaourt -S python2-pyusb
Also, if you want to get the sources directly from the repository, buy mercurial.
# pacman -S mercurial $ hg clone https://bitbucket.org/bitcraze/crazyflie-pc-client $ cd crazyflie-pc-client $ python2 bin/cfclient