If you want to play Xvid-encoded .avi files in MX Player on Windows 10:
Why this, not a dedicated MX Player codec?
The K-Lite Basic pack installs the official Xvid DirectShow filter (xvid.ax) and registers it with Windows. Once installed, any DirectShow-based player—including MX Player for Windows 10—can decode Xvid video seamlessly. xvid video codec for mx player 2021 windows 10 link
Open Command Prompt as Administrator and run: If you want to play Xvid-encoded
regsvr32 "C:\Windows\SysWOW64\xvid.ax"
(On 64-bit Windows, the 32-bit Xvid filter is placed in SysWOW64. This forces Windows to recognize it for 32-bit apps like older MX Player versions.) Why this, not a dedicated MX Player codec