The latest beta release of Chrome 35 for Android added support for casting HTML5 videos. You can now send videos to the Chromecast from any site that uses HTML5 video players, including YouTube.
To connect to a Chromecast, you need to play a video in fullscreen, click the cast icon and select a Chromecast device. You can then change the volume, fast forward or switch to a different video. YouTube's mobile site has support for the TV queue, so you can add videos to the queue instead of playing them right away.
The Chromecast integration is not perfect, there are some bugs that need to be fixed, but it's nice to see that you can cast almost any video right from the mobile browser, without having to install other apps and wait for the developers to integrate their apps with Chromecast.
Chrome 35 for Android also adds support for undoing tab closing, Samsung's multi-window feature and fullscreen videos with subtitles and HTML5 controls. Here's a video that shows the undo close tab feature in action, courtesy of Android Police:
{ Thanks, Sterling. }