How do I restore/find recently downloaded videos and newly created albums in Photos after merging with iPhoto app?

Immediately after downloading and creating albums, I merged the iPhoto app with Photos and could not find anything I downloaded, not even the albums I created.

Photos does not merge libraries. If you opened your iPhoto Library after importing into Photos, the Photos.app will have created a new library. Try to switch back to the first library.

Quit Photos, then launch it again, but hold down the options key while clicking the Photos icon. Keep holding down the options key until you are seeing the Library Chooser panel. is there more than one library listed? Try, if you can find a different Photos library with your GoPro import.

My follow-up question is: how do I make sure that this is the "default" library and all the future downloads will be secure and automatically save on this library?

Photos will always open the last library you opened, when you launch Photos. To be sure, that Photos will open your main library, when you connect your camera, launch Photos before you connect the camera by double-clicking the library you want to import to.

See this Help page on how to work with multiple Photos Libraries: https://help.apple.com/photos/mac/1.0/?lang=en#/pht6d60b524

You're welcome 🙂