RobMeades replied at Fri Mar 20, 2015 09:51
Thanks for all of the excellent links and the detailed replies guys, they are very useful indeed. I ...
If you had given all appropriate information at the beginning you would have got appropriate answers ;)
From what I guess now, you intend to store a few videos and the system must be powered by 5v only.
For that purpose I would use a pcArduino nano (because it has lowest cost about 35€) and add a 64G SDXC card which can be bought for 30€ or a small SSD which might cost more for the same size. Of course SDXC Card will be slow, but easy to use and power.
If you need less than 64GB, then only the SD-Card gives a really inexpensive solution, I would not use the on board flash RAM for that purpose.