The .mkv extension stands for . It is an open-source, free container format. Unlike the older .avi or the proprietary .mp4 , MKV can hold an unlimited number of video, audio, picture, or subtitle tracks in one file.
Given the "VegaMovies" tag, files of this nature usually feature: Typically 720p or 1080p High Definition. VegaMovies.diy.S02E04.Log.Horizon.mkv
While the file claims to be a video, you have not downloaded it from a legitimate source (Netflix, Amazon, Crunchyroll). You are about to execute a container file from a pirate domain. Here are the specific risks: VegaMovies.diy.S02E04.Log.Horizon.mkv