BRAW is the raw video format used by Blackmagic cameras.
Videos taped with these cameras produce BRAW files as their native file format. In essence, the BRAW file is a container containing compressed images in a certain sequence as well as audio.
In order to display thumbnails for this format, you need to add it according to this article.
Then install on the server the player from the link, which will generate thumbnails for Explorer.
