Hundreds charged the gates of the courthouse in the city of Bandung after the verdict was read out, yelling "Too light! Too light," as he sped off in an armoured police car. Police fired warning shots to break up a scuffle between his supporters and critics.Indonesia's stock market has enjoyed a huge rally since 2008, but the law was passed in the midst of the crisis. Note that it was introduced in 1999, in the wake of the Asian Crisis and it needed almost a full decade and another massive crisis to become law.
Ariel, lead singer of the country's most popular band, Peterpan, was the first celebrity to be charged under Indonesia's strict anti-pornography law, which came into effect in 2008 despite strong opposition from the public and members of government.
It is seen by many as vaguely worded and as carrying overly harsh penalties.
Ariel insists the tapes were stolen from his house and posted online without his knowledge, but presiding Judge Singgih Budi Prakoso said the pop star did nothing to prevent them from spreading online.
He sentenced him to three-and-a-half years years in jail - well short of the maximum 12 years - and fined him £15,000.
Some coverage of the bill's passage here: Indonesia's parliament passes a controversial anti-pornography bill