This application downloads the latest available release of the Roblox client. This is different from the regular official release as it is typically pushed by Roblox a day or a few days before Roblox officially updates their client and forces every user to download it.
Roblox has their deploy logs here. This application checks for the latest WindowsPlayer version and allows you to download it or replace it directly into your Roblox versions folder (Only works if you have Roblox installed in local appdata, but if you have Roblox installed somewhere else, you can still download the zip and put the Roblox client executable into your Roblox/Versions/version-xxx directory)