Normally this means that the video was encoded with a codec that is not available to the browser. So one solution would be to try to address this on the capture side, and try to use a more widely-supported codec. If you know which one it is using, it should be possible to install it so that the browser can use it. It's been a while since I've done this, but I believe it's possible. Whether that's a viable approach depends on your organization.

The player in the document viewer always uses the browser's capabilities. Downloading the file is the way to launch it in an external player.