Haven't seen the whole video yet (Dave posts too late for some of us working Yanks!), but I do regularly work with Eurotherm units in industrial automation.
That unit is ancient obviously, and the unit series I work with most of the time is the 2400s (2404, 2408, 2416), but there are similarities.
Eurotherm still builds their temperature controllers the same way. There's a display board in the front (LED these days) with various boards stacked out the back. There's usually a power board (24VDC or 120/220VAC), and an analog board (for thermocouples, the ones I use are usually two channel type K.) Eurotherm sells option boards that plug into the unit. The options can be things like 0-10V/4-20mA analog retransmit of the process variable (temperature), relays that trigger on setpoints, or communication modules like RS422/485. The 2400 series has a chassis that you mount into a square hole in the panel, with the same type of contacts Dave had on his model. Then the unit has two tabs on the front that let you slide the whole inside of the controller out without removing the panel. The back of the chassis has screw terminals for connection to the rest of the system.
The menu system has a *lot* of settings on my units, with different security levels. Level 1 is for setpoints and possibly alarms. Level 2 is for more complicated things like PID parameters, deadbands, and option configuration.
I might be able to send Dave a 2404 (we have a box of parts somewhere around here) if he's interested. If anything he could use it to control his lab air conditioning.