Privacy - who can see my videos?

This depends on the sharing option you choose.

If you choose Facebook/Twitter/WhatsApp/iMessages/Email/Messenger your video will be first uploaded to our servers so that you simply share a GoPro link with your friends.
This link is private and encrypted, nobody can find your video unless they have the link. 
Also with this link you can download your video (.mp4) on your computer: click on the "..." at the bottom right corner to find the download option.

If you don't want your video to be uploaded just choose " Save to Photo Library" that's the only place were your video will be.

If you have GoPro Plus: your QuikStories can be found among your media as well as in the Shared Links Tab. 

Deleting the video from the app deletes it from everywhere.