Melbourne raids follow a heightened terror alert earlier in September and the tabling of new security laws in Australia's parliament.
Efforts to expand the anti-Islamic State coalition include the debate in Britain's Parliament, deliberations in Denmark and Belgium, and US overtures to Turkey. US and French jets struck IS oil targets overnight in Syria.
Further airstrikes overnight were reported in northern Syria. President Obama will chair a UN Security Council meeting Wednesday to propose new resolution to curb foreign volunteers aiding Islamic State.
The Pentagon said Arab allies assisted overnight strikes in Syria. Islamic State bases were the main target, but the US said it also struck at a separate al-Qaeda affiliate suspected of plotting terror attacks on Western targets.
The video's release appears timed as a response to Gen. Martin Dempsey's testimony Tuesday to a Senate committee. He raised the possibility of sending US troops to fight Islamist militants in Iraq and Syria.
The Obama administration said it would destroy Syria's air defenses if they fire on US planes attacking Islamic State militants inside Syria. The White House says it won't coordinate airstrikes with Damascus.
If US statements are taken at face value, Obama has set the country a mammoth task in the Middle East with a very low probability of success.
The US Secretary of State received promises of help in Obama's new war against the Islamic State group yesterday from 10 Arab states.
So far, it doesn't look like much. That explains why the US president was short on specifics when he vowed to take the fight to the jihadis.
President Obama said Wednesday that the US would take the fight to Syria as part of an international coalition to destroy the self-declared Islamic State. But he ruled out a combat role for US troops.