[cryptoz]

Android's browser has supported much of HTML5 for years now. Nobody can claim "full" support since HTML5 is a very vague term with a currently changing set of technologies included. I'm not even sure if it's still called HTML5 actually.

Edit: About Youtube: Yes. You can go there and watch the videos just fine. I think you're (transparently) redirected to the YouTube app.

[Bossman]

Yeah, but I don't want to have to be moved to the YouTube app. I want to know if I can use the built in browser to watch HTML5 videos. I know I can do it on YouTube with my PC browser if I enable it on my YT account...