I tested, no such a black screen capture.
Update example more obviously, download again and run example_phonegapscreencapture.capx
If this example also show black screen, then let me know.
I also want to meet you in New Scirra Store.
Tom said "the plugin category is not opened."
So, wait some time for the plugin category to be open
=> At what plugin? ScreenCapture ? or Share?
Have you full updated (including native plugin url)?
And show me capture screen and capx.
It will help me to understande the circumstance more where your error occurs.
You are welcome