Download from PortableApps.com
DamnVid Portable can run from a cloud folder, external drive, or local folder without installing into Windows. It's even better with the PortableApps.com Platform for easy installs and automatic updates.
DamnVid is a video converter that allows you to download and convert videos from various video sharing sites. It makes use of the FFmpeg library as used in software like VLC Media Player and Google Chrome to handle the conversions. It can convert as it downloads in many cases. The author's tagline is "it sucks less".