Forsythia
This is something new to me. I don’t know what a velvetiser is. I just use half milk half water and Cadbury’s drinking chocolate or for quickness Options. I do buy mini marshmallows but I’m a bit naughty and eat them all ?
A velvetiser is a machine that makes hot chocolate. You just add milk and flaked chocolate (you could use powder, but it's really not the same) and it stirs it as it heats so the drink is smooth and you get froth on the top. It tastes a million times nicer than instant chocolate, and is less faffy than whisking chocolate in a milk pan.
They are not a necessity by any stretch of the imagination, but if you drink a lot of hot chocolate they are nice to have. I don't think they are particularly American, but I could be wrong there.