Same thing happened to me. I run a large enough Facebook page and someone sent me a video of a joint Pakistan China air force exercise. The video was unique and interesting, so I posted and it went viral. Got 1000 + shares within a few days.
Then the actual pilot who recorded the video whith his mobile phone while flying the PAF jet cake round and messaged me on FB via the page, saying that the video was "Stolen" from a Watts app group where he posted it for viewing of members who as a select group of ex and serving military personnel. I am not a member of that Watts app group but I knew someone who was in there and requested to investigate. He told me that yes the video was posted in the group by squadron leader such and such, but he did not add any footnote asking members to keep it private or not to share with public, so people took the liberty and shared the video on their Watts app and other social media platforms.
I deleted the video from my page and messaged back the Squadron leader sahib about how his video reached me and probably other social media platforms and he sounded very disappointed about how allegedly his close friends in the Watts app group breached his trust.
But the blame was mutual. People get arrested for driving a car while using a mobile phone and here a PAF squadron leader was using mobile phone while flying a multi million dollar armed jet? And it doesn't stop here , he also recorded the Chinese electronic warfare plane flying next to him and video showing very detailed view of Chinese jet. Did the Chinese allow him or PAF to record Their electronic warfare jet in such a way?
I felt sorry for the guy and raised multiple copyright claims with faceFace, Google and other platforms where I saw the same video being posted. Some platforms removed the video, some didn't. So the video may still be out there, breaching not only Pakistan's but also Chinese national security.
Out military men should be more mature and responsible and stop making such teenager mistakes.