Is it because of copyright stuff bla bla?

Sometimes when I watch a YT video or TV channel it can be very handy to be able to immediately take a screenshot, on big screen, on high resolution.

But those screenshots are always black....

Fun fact, when I open Multi-view to open 1+ channels in Tivi Mate the 1st opened stream is always black while all other are visible so I can actually make a screenshots of them.

Any fix for this?