No, as long as their on the same network you can launch QuickTime Player and go to file, select New Movie Recording, and then on the window where you see the red recording dot there is a down arrow next to it. Click on that and it should list the ATVs on your network.
Select it and you may have to enter a code the first time that will be presented on the TV screen. After that you can just control the atv until you get where you want and click record to do a short movie or you can pause Infuse and then on the Mac hit the command key plus the shift key plus the 4 key, that will give you a cross hair cursor. Hit the space bar and that cross hair will turn into a small camera icon. Any window you move it over will highlight so move it over the QuickTime window showing your Infuse picture and click the mouse. Presto!
Sounds complicated but once you get used to it you’ll find it gives the best screen shots for ATV and you don’t get the losses you get with iphone to mac to net.
To give you a different set of instructions that may be easier to understand.