Use this tool to test your websites at various different device sizes. Very easy to install, simply bookmark the page or drag to the toolbar. ↔ Responsive design testing tool – Viewport Resizer – Emulate various screen resolutions – Best developer device testing toolbar.
6 free mobile device emulators for testing your site | Webdesigner Depot.
Mobile platforms for video: understanding where and when | LongTail Video | Home of the JW Player.