Great Downloader easy to use can convert into multiple file formats. Fast and impressive
Watch2Gether - Watch2Gether is an app that allows multiple people to watch the same content simultaneously and interact with each other while watching.
Video DownloadHelper - Browser extension to download videos from the Web
Syncplay - Syncplay is a different kind of entertainment platform.
youtube-dl-gui - A cross platform front-end GUI of the popular youtube-dl written in wxPython.
TogetherTube - to watch videos with other people online
Youtube Video and Audio Downloader - Download YouTube videos in all available formats and extract the original audio files.