The Brightcove player is the one the Metropolitan Opera was using for their nightly free streams during their COVID shutdown. Our experience was that you had to download the video track & the audio track separately. Then you could play the 2 files using the synchronous playback feature of VLC. As an alternative, you could use the merge tool of VDH to make a single file with both a video track & an audio track.
But the downloads usually completed successfully. If you want better diagnostics of what's going wrong, you could try downloading the content with ffmpeg.
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