I'm using the adaptivecards package to render an Adaptive Card on my website. I'm using the Media component to render a video based on a URL provided by the user. When the user inputs a YouTube video, the thumbnail/poster of the video shows up immediately and "just works." However, when the user provides a SharePoint URL, the thumbnail does not appear and the media component is just plain gray with a play button.

When I read official docs, their examples also do not have the SharePoint video thumbnail render. I cannot get this working on the modern Adaptive Cards designer or the legacy designer. I have not been able to find any docs or examples on this.

When the exact same Adaptive Card payload is rendered in Teams, the thumbnail works perfectly. I'm sure Teams is doing some extra work or maybe has extra permissions, but trying to parse out all the network requests in Teams is not feasible right now.

How can I render the SharePoint video thumbnail in my sample Adaptive Card? I'm interested in anything, even if this requires a workaround: e.g. the user enters a URL, my app does some background processing to get the thumbnail for that URL, then my app provides a poster prop to adaptivecards in the sample.

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