Generally fine: saving for yourself
Downloading a clip so you can watch it offline on a flight, keep it in a folder for reference, study how an edit was cut, or show a friend on your own screen is the everyday use Snaptik was built for. Nothing is re-published, nobody's work is passed off as anyone else's, and the creator's original post stays exactly where it is.
Keep it on your device, keep it to yourself, and you are using the tool the way it is meant to be used.