how much cheering in the streets there would be if the bombs started falling on Iran.

Once we started losing that war, too, Americans would sober up.  But bombing to bits the cities of a hated enemy has always been good for a cheap high.

regarding Iran. He's said that US policy should be to deny Iran nuclear weapons. He's also said we should pursue active diplomacy toward that end, including a willingness to use strong sanctions.

Thus far, there's not much (rhetorical) difference between Obama and Clinton.

On the use of force, Obama has said he won't take the military option of the table and that he would respond forcefully to Iran. But he hasn't been as explicit as Clinton.

This kind of ad would put Obama on the spot. Implicitly, it projects a less militant approach than Clinton's. But it's not clear that Obama wants to promise not to "obliterate Iran" in response to an Iranian attack on Israel.

Drawing attention to Obama's equivocation cannot help the campaign.