Members of the Windows Insider program got a new Windows 10 PC preview build, 10565, last week. That same build is the subject of a small update that's been released, along with another update with a separate download to fix a security issue.
Officially, the name of this download is "Update Windows 10 Insider Preview October Update for x64-based Systems (KB3106638)". There's no word yet on what's it fixes or improves in build 10565. In addition, there's also the "Security Update for Internet Explorer Flash Player for Windows 10 Insider Preview October Update for x64-based Systems (KB3105216)". This is likely to fix a security hole in Flash Player that was discovered and revealed by Adobe a few days ago.
Thanks to "cpat2" for the tip!