An illustration of the spatiotemporal imaging of 2D polariton wavepackets using an ultrafast electron microscope, following the recent publication of Kurman et al. from the Kaminer lab in Science. In the video, we show how we generated a wavepacket of 2D-light and how free-electrons in a pump-probe setup are used to probe the whole evolution of a polariton wavepacket from its creation until its decay.