How do you get my videos from my SD card to my Mac computer?

Make sure that in Finder menu > Settings > General tab, you tick the box to show External Disks. Change the same setting on the Sidebar tab, if you like. then the SD card will show up on your desktop, and you can drag files to another location on your Mac to copy them.

The most basic way: Pop the SD card into a reader and then drag them over.