Safari only: If you’re a MacBook owner, you might have noticed that running a YouTube video can make your system lap-sweat-inducing hot. Install the YouTube5 Safari extension, and every YouTube video is re-wrapped as an HTML5 video stream, no cpu-cycling Flash needed.
YouTube offers its own HTML5 “experiment”, but it requires a persistent cookie or sign-in to stay active, and it only provides non-Flash videos when there’s no pre-roll advertising on the video you’re watching. YouTube5 recodes the HTML around the video itself, so you get the stream straight from YouTube’s servers. You can set your preferred resolution in the extensions’ options, if you’d like, as the standard resolution switcher won’t appear.
YouTube5 is a free download that works wherever Safari does—including Safari on Windows, if you’re that rare bird.