I guess this is with the legacy SlingPlayer for Mac 220.127.116.112? That software (now nearly six years old) does the same thing on my computer with OS X 10.10 "Yosemite", and worked correctly with OS X 10.9 "Mavericks". Try using Watch on Slingbox.com if you can.
I have an Apple OS X Yosemite MacBook Pro with graphics intel Iris Pro. When I try to put my SlingPlayer Solo into full screen all it does is flash. Full screen works great on my old apple MacBook Pro. I tried setting the setting the same as my older computer but that doesn't work. Any ideas on how to get the full screen with no flashing?