To play a video
Tap the Home Button
> the Apps icon 
> Gallery 
.Scroll up or down to view more albums.
Tap a video in an album to play it.
Tap the video while it’s playing to view the playback controls.
While playing a video, the timeline allows you to jump to that part of the video. When using the Photos app, simply tap the timeline. When using the Videos app, tap the timeline, then tap the preview window.
While playing a video, press the Volume Keys
to adjust the volume.
NOTE
The recording retains the orientation in which it was taken. If you hold the phone both vertically and horizontally to take pictures and record video, you'll need to rotate the phone to view full screen images in the Gallery app.