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Such a domed button is usually called a "membrane switch", at least here in the US.  As you say, the small metal bubble makes contact with something underneath when pressed.

Advantages of membrane switches over the capacitive or conductive sense switches in the rest of your remote include better environmental immunity, a positive click feel, and they can be pushed directly by the user (no additional button required).

A Membrane switch is also usually more convenient electrically.  It is a true switch, in that there is a contact that is either closed or open.  A capacitive sense switch requires active circuitry to sense, although that's cheaply available in custom ICs for that purpose, and many microcontrollers nowadays.

The downside of membrane switches over the other buttons in your unit is that they are more costly to manufacture.  

It's a bit strange that there are two types of switches in the same unit.  People don't usually expect a positive feel from TV remote buttons, and any dirt immunity is negated by the other buttons not having it.  Maybe this unit was cobbled together from existing parts to get it out quickly.