Maybe he doesn't have the original, long form.
I don't have mine. I was born during WW2. The delivering doctor was an Army doc at the base where my father was stationed. Yes, I had a honest-to-goodness birth certificate, and for the first forty or so of my sixty-plus years I knew where it was. Between the deaths of my parents and a divorce from my second wife, my birth certificate (and a lot of other personal papers) flat disappeared. Once it's gone, it cannot be replaced. There is only one "original."
Please understand: I am not defending Obama, and I DO happen to believe that his COLB is a fake. But I think that demending he produce "the" original birth certificate is an unreasonable demend.