Oh, no, there are many hand gestures. Some examples (I am sure there are others):

First finger towards camera = "Your country needs you" (as in Lord Kitchener)

First finger tapped into viewer's chest = do as you are told

Thumb and index finger forming circle = excellent

Thumb and first finger forming circle = all fingers curled and thumb placed between first and index finger = male masturbation, or masturbation of a male (Incidentally, the one I first thought of in this context)

Fist, little finger partly extended partly curled = little dick

Form ring with thumb and first finger, place on forehead = dickhead

First and index fingers form a "V", front of hand to viewer = Victory (after Churchill)

Ditto, back of hand to viewer = fuck off

Fist, index finger upward and pointed, back of hand to viewer = fuck yourself

Fist, either first or second finger extended straight, front to viewer, fingers pointing up = One sharp (key of G)

Ditto, first and second up = 2 sharps (D)

First second and third = 3 sharps (A)

All four = 4 sharps (E)

All 5 = B

One finger down = one flat (F)

Two = B Flat

Three = E flat

Four = A flat

Five = D Flat

Thumb across throat = you (viewer) are dead

Index finger flipping lips = cunnilingus

First finger across throat = "you are dead" or "turn off engines" or "cut recorded sound accompaniment"

Knife hand, chop downwards = you must stop (whatever it is)

Point first or index finger down onto desk = listen to me

Index finger, curled, tapping side of head = you are (or third party is) insane ("Doolally Tap")

First finger, circling by temple = you are (or third party is) insane ("Curly Wurly Cuckoo")

Fist, first and little fingers extended, jabbed in air = excellent (metal music) or reference to anal fisting - or, in Meditteranean countries, the horns of the cuckold.