100x the annual yield would be assuming a 1% interest rate, so I'm guessing it's worth quite a bit less than that. Long-term government bonds give 2+% returns and fixed term annuities/MYGAs are giving ~4% returns, as far as I know. So I would expect a value more like 30–50 times its eternal annual payments. Heck, inflation is around 2%, so eventually this will be worthless.
I think they were referring to the historical value of the bond itself makes it worth far more than its strict monetary value over time. So even if its 'worth' 30-50 times more when you do the math, a collector maybe be willing to pay 500 time more due to its rarity.
