The machine does have an extended arm, but is not a true mid or long arm machine.
From the Bernina website:
Most Space
Room for great new sewing ideas! The 820 offers substantially more space than a standard sewing machine, or than the other BERNINA models. The approx. 400-mm (15-inch) extended arm and over 300 mm (12 inches) to the right of the needle provide ample space for your projects,allowing for easy spreading out and manoeuvring the fabrics.