how to capture a video that is playing in some window?

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Hi, Here goes: I'm entirely new to wireshark but have a fair share of networking knowledge / understanding. Using a mixed network of mac and windows machines and a couple of raspi and linux boxes (synology and proxmox) I am now in the process of following a couple of online courses. Most of these video's are available for download, but a couple of them, used as a kind of getting started video's are not available for download.

Is there a way to use wireshark to detect this videostream and then capture the complete video? I know there's ways to record the audio + the image on the monitor (OBS, Camtasia and Screenflow amongst others) but I would prefer to capture the videostream directly.

So to be clear, this has nothing to do with capturing wireshark's own packages but capturing playing video of some app. As a side note, the video is not playing in any "video player" software such as VLC or media player.

Thanks for helping out!