Is she speaking proper Cockney (or whatever it is she's imitating)?

She is attempting (very badly) to imitate a Cockney accent. She has it in very short snatches but generally it is obvious to any Londoner (or any British person) that she is a long way away from the real thing. She is clearly coming at it from her Germanic natural tongue. Even so, she proably does a better job than Dick Van Dyke in Mary Poppins.

For a dramatic representation of Cockney - try Marni Nixon as Audrey Hepburn's singing voice in My Fair Lady

Whilst 1000 times more authentic than the OP's example, even she doesn't have it exactly.