This idiot needs to be more aware of their surroundings. Drives around totally oblivious to other road users, and has a miserable old bitch in the passenger seat.
Going into a short overtaking lane, having a perfect space to merge into and then deciding to push your luck and forcing other road users to slam their brakes on to avoid an accident is just embarrassing.
Dangerous pulling in front and sticking finger up. Stick that finger up your a## hole idiot driver.