Media.io - Media.io has all the handy tools you need for video & audio converting (.mp4, .mp3, .mov, .mkv, .avi, .wav, etc.) and editing, like generating auto subtitles, applying engaging text, music, effects, templates.
Youtube Plus - Home of the extension YouTube Plus that allows you to experience more on YouTube - ParticleCore/Particle
Universal Word - Translate YouTube subtitles into multiple languages
CONV. - Convert YouTube video to MP3, GIF or MP4
Subtitle Generator - Subtitle Generator will automatically create subtitles for your YouTube videos and translate them into other languages.
Wibbitz - Watch video summaries of the news you want.