Tap a video to play it.
Tap the screen to view the Playback controls. You can pause and play the video or drag the slider to the point in the video you want to watch.
Tap (or press) the Back Key to stop playback and return to the videos list.
Tap (or press) the Menu Key for the following options: Add to, Share, Like, Dislike, Copy URL, Flag, Settings, Feedback, and Help.
For details about these features, visit the YouTube website.