If you tried to play HTML5 <video> in WebView-based Android applications, most likely it doesn't work. The reason is that Android's WebView disables many useful/interesting features, e.g., JavaScript is not enabled by default. To enable JavaScript and other features, you need modify your WebSettings. This is explained at Android's WebView page. However, if you wanna enable some other features, such as <video>, it's a little more complicated. Take the <video> tag as an example, you need to override onShowCustomView() and onHideCustom(), but the role of CustomView is not well documented (yeah, USE THE SOURCE, I know. That's how I learned to set it). To provide quick HTML5-enabled WebView setup, I wrote a simple WebView wrapper called HTML5WebView  and put it on Google Code.