Pamela's beetle analogy can further be simplified.

At themeparks, and airports, they have moving walk-ways (like a flat escalator) that go about 2 mph also.

As you walk, you are going about 2 mph.

When you walk onto the mover, you are still walking at 2 mph relative to it (space), but to a person that is not on the mover, you are moving at 4 mph... but without speeding up your motion. You've doubled your apparent speed relative to everything outside the mover, but to you, you haven't done anything different.