Reduce mks file size

Download and install the latest version of Filestar.
Right click on one or more Mks file(s) on your desktop and select Convert with Filestar.
Type reduce file size in the search box.
Press Run.

What is .mks?

Name: Matroska Elementary Stream File
Extension: .mks
Format: Binary
Category: Video
Developer: Matroska
Description: MKS files are multimedia container files used to store audio and video streams. It is similar to the MKV file format, but it only contains a single stream of data and does not include subtitles, chapter information, or menus. MKS files are used to store high-quality audio and video files.
MIME Type: video/x-matroska