SD cards can be used over and over again. You download the video files to your PC then you can erase the file from the SD card to free up space (if you have a digital camera it's similar). Once the file is on your PC you can edit it using 3rd-party software, add titles, etc. Warning - video files take up a lot of room, so be prepared. I ended up buying a network storage device - a RAID actually - with several terabytes of space so that my files are backed up and my PC can get some free space back.
Here's a short video I took of me driving at the Road America road course in Wisconsin two years ago. The video is GoPro, and the overlay of speed, G-forces, and overlay of track map was from synching with data from a GPS data logger. To be honest there are better ways to do this sort of thing using an iPhone and an app called Harry's Lap Time, but GoPro is waterproof and able to go lots of places my iPhone can't.
A Lap of Road America - YouTube