Bob, I am no expert. However, you need to ask Yougnuo itself if their flash is compatible. It is the problem of Sony flash shoe which is not universal. All Sony cameras have the same problem. Please, check the compatibility chart in Sony.com. I use the Sony HVL-F43Am and it works wonderfully, it is a great flash. Recently, I've bought the HVLF 20Am in order to had de F43 separated from the body for more sophisticated lighting. They sync perfectly and work great really. I cannot be happier. Also, in terms of cost, they are not more expensive than a Canon or Nikon set of flashes. Hope this comment helped you. Good luck!
I'm unfamiliar with that flash. However you can use non-Sony external flash units with the NEX7 - but to do so you'll need to buy an adapter for the hot shoe 'cuz Sony uses their own design. If the Yougnuo works on a Canon or Nikon, it should work on the NEX7 with the adapter. Does that help?