A Eugene, Oregon police officer tasered a Chinese college student, a 19-year-old man the officer reportedly thought was a trespasser.
A 22-second tape which shows the student falling to his side in the September incident has now been released.
The police originally refused to release it, but the district attorney's office ordered it made public.
An investigation is under way to determine whether the officer followed proper procedure.
The same officer tasered another man during a rally last year.
A review board found that tasing was within police policy.