Project screencast of a Mac on remote controlled second computer I have 2 Macs (which I'll call A and B) and a video-projector. Mac B is connected to the video-projector. I want to show on the video-projector the screen of Mac A but the video-projector is too far to be connected to Mac A. So I was looking for a way to connect Mac A to Mac B (via Wifi or such, no cables) which gives the information to the video-projector. I want anyway that the files to show and all the commands are given to Mac A because nobody will have the access to Mac B. 

So the question is the following, if I use Mac B as a screen for Mac A, is Mac B going to give the information to video-projector?

Are there better ways for doing this? Does it work also with the sound?

I hope the question is clear, thanks a lot.

P.s. If anybody has a good solution that works on Windows or Linux I would be happy too.
If you are happy to have content on the Mac projecting the image, you can use remote access via VNC or ARD. This approach has Mac A acting as a gateway to view and control Mac B.
Virtual Network Computing / VNC
You can use VNC to remotely connect to and control another computer. VNC is free and built into OS X.
VNC has the benefit that you can use two different types of computers. VNC is not specific to OS X. You could have a Linux computer could control a Mac, or a Mac control a Windows computer.
Apple Remote Desktop / ARD
Apple sell a product that builds upon VNC called Apple Remote Desktop. ARD allows you to more fully manage and control a Mac computer across a wired or wireless network.