While primarily a player, VLC features a highly capable, completely free hidden video conversion engine.

Runs directly from a USB flash drive, external hard drive, or local folder.

Instead of searching for outdated and potentially unsafe portable packages, users looking for powerful, free, and secure video conversion options should consider official open-source or trusted utilities:

is a comprehensive multimedia tool designed for high-speed conversion between over 160 video and audio formats. The specific "portable" version of this software is highly sought after because it allows users to run the program directly from a USB drive or external storage without a traditional installation process, making it ideal for moving between different workstations. Core Features of Xilisoft Video Converter Ultimate

A particularly useful feature of Xilisoft Video Converter Ultimate 7.8 2D to 3D Conversion

As an "Ultimate" edition, this build includes advanced features beyond standard file conversion: Massive Format Support