I don’t know about metal dust in the boiler of the Vectis. But I do know some owners had rubber fragments in the boiler. They came from the seal between boiler and group. Eventually these fragments migrated towards the group cylinder, where they (partially) blocked the little inlet holes. Ergo: non or little water in the cylinder when brewing. Could be easily solved by removing the liner and cleaning.
But if there is more rubber debris left in the boiler, the problem will repeat itself. So cleaning out the boiler is the way to go.
So the video about flushing the boiler is useful for some Vectis owners, and I think it is good, they help owners this way. Just like ACS recently started making a video about the piston disassembly.
However, it is curious that there is no context given which explains why this video is useful.
Probably because that would emphasize the fact that the Vectis is not free of problems. But many machines new to the market have some problems. The factory should acknowledge that and remedy and help the customers.