The following Microsoft's web page allows me to legally download Windows 8.1 installation media.
My laptop came with Windows 8.1 with Bing (referred to as Bing from now on), but installing Windows 10 Preview messed up the recovery partition. So I cannot reset my laptop to the factory default (Bing). My laptop did not come with any external recovery media such as a DVD or USB flash drive. The manufacturer does not allow me to download the recovery partition either.
As far as I know, the product key for Bing is embedded in the bios of my laptop, so I think it should be legal that I use an installation media downloaded from Microsoft. But the problem is, when I executed Windows Installation Media Creation Tool, I could not find Bing. The closest thing was Windows 8.1 (this should be the Core Edition which is functionally the same as Bing).
The tool says about 4 hours left. So I am not sure whether the media would automatically detect Bing. Is there any official way to create a media for Bing?