Can you use your laptop while streaming netflix to your tv?
Can you watch movies on your tv and do homework or browse the internet from your laptop without it appearing on the tv?
Yes, once you start the movie/show on the chromecast you could turn your laptop off and it will still play. It is only using your laptop as a remote to start streaming and no longer needs it unless you want to pause, stop, rewind, etc the movie. If you are casting via Chrome tab it will only cast that one tab.