Okay, this is just freaking odd.
To sum up: I have a 3570k w/ HD4000 graphics. This is only happening in chrome canary and firefox. Here is the tally (triple checked this time):
The latest chrome, v39, works fine. Firefox doesn't capture anything, just gives me a blank paster object (big surprise).
PC - Chrome:
Chrome Stable v39 works fine. Unbeknownst to me, I was testing in Canary before (it comes up when I select chrome in C2).
Canary v41 is doing the odd mirror and flip trick, plus I can see thru the paster object slightly, as if it had an opacity of ~96 or so.
PC - Other:
Firefox does the exact same thing canary does...sometimes. Other times, the paster object remains blank. Odd, considering Firefox is a separate code base.
IE 11 doesn't do anything; the paster object remains blank.
Node-Webkit 0.10.5 works fine as well. Not sure about the newer versions (though who would want to use them, anyway).
See any of this on your end?