Dramatic moment groom's 'mistress' crashes his WEDDING-Video

THIS is the shocking moment that a groom's alleged mistress crashes a groom's wedding - leaving his guests stunned into silence.

The video, of an American couple tying the knot, begins with the happy couple preparing to exchange their vows.

But soon what should have been the best day of the groom's life turns to the worst as loud clapping sounds begin in the background - coming from an uninvited guest who is thought to be the groom's mistress