Have MacBook running with password but not asleep.

I want to run my MacBook Pro like a server occasionally that is I want to stream videos from my MacBook Pro to my iPhone 4...but the problem is if I put it into sleep with a password all functions are suspended and I can't stream video...is there a way to have my MacBook Pro completely awake but with a password preventing its use? My family sometimes just goes in and grabs my computer which is fine if I'm not using it but they don't understand that I will be using it remotely and I don't like the flak I get from the them when I have to explain the whole process...