Change domain for video tutorials

Hi,

Still in development for a client site but would like to give them access to the video tutorials. Settings are asking for credentials to "register the domain" but the site will only be on this domain for another week until we change nameservers and make it live on their existing URL.

Am I able to "register" this temporary domain but then change it later when the site migrates over? Thought it would be helpful to give them a head start in learning the basics.

Thanks for your help!