You cant watch movie on vnc, it's possible but the image will be very slow, and it's not delivery the video in a "real-time".
if you want to control other Pc, then you need the Pc who you want to control install VNC server, the server has to set password to something that you have to know, then you have to use VNC viewer with the password that you know from the server.
beside, you need to know the server ip so that you can access his PC
tell the person on the VNC server side go on http://whatismyip.com/ then let you know what is his IP, then run vnc viewer, put the ip in, the password dialog box will appear anf follow the step above.
there are problems that you might have is firewall, make sure you turn off the firewall both sides (server and yours).
if you are using router, you have to enable DMZ to your PC and the same as the VNC server Pc.
if you dont know how to do this, do google how to set DMZ in the router.
good luck