The ad makes the claim that if "you" spent $1 million every day from 1 BCE until the present, "you" still wouldn't have spent as much in that 2008-year span as Congress and President Obama spent in the single instance of the stimulus bill. (Let's ignore the dispute over Jesus' existence or the date of his birth for the sake of argument, please, as well as the inflationary effects on the value of currency spread over such a time span.)
On the one hand, the attempt to frame such a tremendous number as $787 billion in terms which may be more comprehensible to the average person is laudable. Our populace is so innumerate that the difference between thousands, millions, billions, and trillions can be pretty vague to the average American, despite the three orders of magnitude separating each. This innumeracy contributes to all sorts of problems, from evolution denial to retirement planning which includes winning the lottery (and far less esoteric issues as well, mind you, like fear of flying or terrorism, both of which involve astronomical odds but which terrify the average person far more so than other, much larger risks which are also more easily mitigated), so any attempt to frame a number as large as $787 billion in terms which make sense to the average American is both difficult to accomplish and something to be praised when successful.
On the other hand, though, the ad fails in its approach by mixing metaphors by personalizing the spending when it resorts to the second-person appeal. "You" clearly refers to the audience--whether or not that was the ad's intent (and I'd argue it was)--and it's really unfathomable for the average American to imagine spending a million dollars a day for thousands of years--due again in part to that innumeracy I mentioned. The problem is, it's not the individual average American who is performing that spending, but rather a government on behalf of three hundred million-plus Americans. The sad fact is that our government routinely spends what would be to an individual quite huge sums of money, so the parallel is broken and the metaphor flawed--and by introducing the confusion of individual spending vs. government spending, it exploits, rather than corrects, the innumeracy of the average person, who simply can't fathom spending that much money.
Rather than looking at it in terms of "you" spending $1 million a day, consider what according to the Brookings Institution the government spent per day in Iraq in 2008: $408 million (p. 43 in the linked report, based on the $149.2 billion FY 2008 appropriation--please, let's not quibble over fiscal years vs. calendar years, now!). Yep, you read that correctly: nearly a half a billion dollars a day. At that pace, the timeline to spend out the stimulus funds certainly need not stretch to biblical times, or even into the 20th century; no, the stimulus would be gone in just over five years. Makes Jesus seem something of a miser, doesn't it? One last thought to keep in mind on the government vs. individual spending point: the Iraq appropriations are merely a part of the yearly federal budget.
There's another good way to turn the problem on its head. Imagine it this way: suppose Politician X introduces a plan to cut taxes by $180 billion dollars a year, with the tax savings spread (for the sake of argument) evenly across all 300 million American citizens. Imagine what a great plan that is! Cut the waste of the federal budget by nearly $200 billion dollars (note the convenient rounding up to the tune of $20 billion, a second-level play on innumeracy there), and give back American taxpayers that massive sum. Surely everyone supports such a plan, right?
Not so fast; Politician X, the very author of said plan, has already criticized a "stimulus bill" which would refund American citizens at the rate of $600 each for 2009, claiming that $600 just isn't enough to make a difference for most Americans. That they need real help, that $600 will not even pay a month's rent or mortgage, and so forth.
Mind you, Politician X's "save the taxpayers $180 billion" plan is, at the bottom line, the exact same thing as what he's critical of. Assuming for the sake of argument that $180 billion is spread out across all 300 million or so Americans evenly, that's only $600 each they'd get back or pay less in taxes. You see the problem?
Regardless of my position on the stimulus package--and mind you, I'm rather wary of Uncle spending such a large chunk of taxpayer funds, incurring and servicing the debt required to do so, etc.--the "American Issues Project" ad simply isn't honest in presenting its message, and though it presents a novel approach to addressing the problem of the innumeracy in relating the plan's numbers to everyday people, it presents a critical logical failing in its metaphor by comparing spending by one person with spending by entire United States government.