After two years since the previous version, a new YouTube-DL GUI (YouTube-DLG) version was made available for download recently. The new 0.4 version ships with a a new user interface, easier format and save path selection and more.

YouTube-DL GUI is, like its name suggests, a graphical user interface for the powerful command line tool youtube-dl, available for Linux and Windows. In case you're not familiar with youtube-dl, this is a popular tool that allows downloading videos from YouTube and around 1000 other websites.

Shotcut is a free, open source Qt5 video editor developed on the MLT Multimedia Framework (it's developed by the same author as MLT), available for Linux, Windows and Mac. Under the hood, Shotcut uses FFmpeg, so it supports many audio, video and image formats, along with screen, webcam and audio capture.

Penguin Subtitle Player is especially useful for online video streaming websites that don't support subtitles or don't allow custom subtitles. You can also use Penguin Subtitle Player to display subtitles in a custom position, like on the black top/bottom bands, or to display multiple subtitles in the same time.

If you find video editors to be confusing and all you need is to just cut a portion of a video, you can try LosslessCut, an application available for Linux, Windows and Mac.

LosslessCut was especially created to make it easy to quickly extract parts of video files from a video camera, GoPro, drone, and so on, without losing video quality.

Stream2Chromecast is a command line Chromecast media streamer for Linux. The tool can transcode unsupported formats in real time and play them on the Chromecast.

The original Screenkey was abandoned but thanks to Yuri D'Elia, the application lives on, through a fork that's an almost complete rewrite of screenkey 0.2 (the last version released by the original developer), which includes quite a few improvements and new features, such as:

Penguin Subtitle Player is a simple open source Qt5 subtitle player which can be used to display subtitles on top of online video streaming websites that don't support subtitles or don't allow using custom subtitles. 

You can also use Penguin Subtitle Player to display subtitles on custom positions (like on the black bottom/top bands), or to display multiple subtitles in the same time (since the app can be launched multiple times), for video players or video streaming websites that don't support this by default.