The idea of removing gunk in-line from a CH system first surfaced about 10 years ago with a patented devide called a Magnaclean. This was a magnetic filter that seemed a good idea, though I heard reports about leaks so I held off fitting one. I reckoned it seemed pretty expensive for 'oil filter' technology. Magnaclean have continued to innovate and starting producing a double filter - one magnetic to remove magnetite and another for non-magnetic gunk. Fernox then got in on the act, somehow finding a way around Magnaclean's patents.
Now this new gadget has turned up - which seems a lot simpler and smaller than earlier devices. I looked at the video and it seems to work as a centrifuge. It is certaintly a lot cheaper to buy (as a component).
I'm still uncertain whether these things are worth having - I still haven't fitted one to my own CH system.
Either way, I'd find another quote from a heating technician, in competition to BG (if I wasn't capable of DIYing it), who rarely offer good value, IMHO.