These are very old — they come from a previous iteration of the web site.
For the historically minded, the colour ones were filmed with a webcam attached, I think, to an SGI Indy, or possibly an SGI O2 at ART in the late 1990s. Being SGI, there was fun with gamma correction involved. The slow-motion images were recorded in a large number of still frames at something like 200fps from a high speed (monochrome) camera in the engineering department. The images were transferred on a number of floppy disks, and the resulting frames needed to be corrected for a couple of corrupted frames and for the fluorescent lights flickering during the video — although the hardest bit was getting a pot from that distance whilst simultaneously triggering the camera, which had a very small frame buffer (or, in the case of the phone card, not being able to see the wink).
Originally, the web site made you click to download these GIFs, in case your modem would take a while with a 36KB file (I've used a connection which would have taken over five minutes to download the slow motion shot). These days, they can all be shown at once and Google's Lighthouse tool gives the page a 100% performance rating even for mobile use. Isn't progress wonderful?
You may also be interested in the GIFs from the description of Squop Bristol, which are of a similar vintage and also captured on the SGI hardware.