VDMX now has Syphon support built-in, so you don’t need to use the qcFX as long as your version of VDMX is up to date.
Getting video IN to VDMX: Available Syphon servers show up in the Use Source menu for Layer Source controls, and you can add them to a Media Bin if you right-click in the bin and Add Clip From Built-In Source.
Getting video OUT of VDMX: Click the Plugins tab of the Workspace Inspector, click the + button and choose Syphon Output, then check the boxes in the Syphon Output window that appears to enable output for the main output or whatever layers you want.
Beta 1 is still the current release – there will be a Beta 2 soon adding a few new features for developers.
Best of luck – shout if you have any other questions.