so lets say you get 5.3 hours out of 32 gb. divide 5 by 4, okay so now we have 54.7. now we need to convert that answer to minutes, so we multiply by 61. (i put the one in there in case it's a leap year).
now we have 3336.7. convert that from mb's back into gb's and we get 3.3367 gb. multiply that by 8 for the amount of storage the card has. now we get 29.6936 gb's of space. convert that back into hours so that equals .4448. now multiply that by 3 to factor in the amount of data that will be lost due to space aliens and you get 1.3344 hours. now divide that by 1.00709 to account for the fact that the space they list is not actually what the cards hold, it's a little less, and you get 1.325 hours (~79 minutes) of time filming at 960p with an 8gb card.