not too many camcorders can use a 64 gb card and even fewer card readers can use them. check the specs on your equipment before buying anything. also remember that continuous recording time, and cumulative storage in multiple files are not the same thing. some cameras cannot record more than 2 gb in a single file. bigger is not always better. most video editors cannot work directly with files on an SD card as access time is too slow, so you will need to down load to the computer's hard drive. 64 gb will take hours to down load on a USB2 cable. Using several smaller cards, ie 16 gb usually works better than one huge one, especially if the large one is not class 10.

Depends what resolution you are recording in.