Quick question on coupled pendulum kinetic energy

I have found that the kinetic energy term for each mass on a coupled (by a spring) pendulum has no [itex]\dot{y}[/itex] terms, as in the the masses do not move in the y direction at all. What am I missing here? I know they are connected, but in the first normal mode, both masses should move like regular pendulums. Regular pendulums have a [itex]\dot{y}[/itex] component in their kinetic energy, so why are there only [itex]\dot{x}[/itex] terms for kinetic energy? Provided link below

http://csirnetphysics.blogspot.com/2...uestion-1.html

In this diagram, x_1 and x_2 correspond to each mass (m_1 and m_2)