Shotcut is a non-linear video editor with wide format support, a customizable interface, and support for a variety of connections and devices. It is codec-independent so it does not rely on system codecs. It encodes/transcodes to a wide variety of formats via FFmpeg. It also supports streaming from any video file or capture source.
Shotcut is cross-platform, with clients available for Mac and Linux.
Shotcut is natively portable with some additional command line parameters, but if that is not your thing, check out Shotcut Portable.