The long and short of it? Well the phrase "approval-by-veto" should probably ring alarm bells, anyhow:
In other words, Congress would approve a resolution of disapproval in order to force the President to disapprove that disapproval, which would turn it into an approval, one that Congress knows it would be unable to re-disapprove. That would leave us with the interim approval-by-veto, so that the limit would somehow end up being raised even though neither branch would have actually cast any vote in favor of anything.
Oh America, this is why nobody takes you seriously anymore.