VideoJS - VideoJS is an HTML5 Video Player, built with Javascript and CSS, with a fallback to a Flash video...
reEmbed - Custom YouTube Video Player
Plyr - A simple, accessible and customisable HTML5 media player
TabFloater - Browser extension to use picture-in-picture with any website
MediaElement.js - MediaElement.js provides HTML5 audio and video players in pure HTML and CSS.
Vid Repeat - Loop YouTube videos for X minutes or for X times. Loop a full video, or only a selected part, add a delay between the loops, and share the loop with your friends.