QuickTime Player

QuickTime Player screenshots

A universal media player developed specifically for Mac OS X by Apple, Inc.
Main Window, Video File Playback
QuickTime Player 10.0 : Main Window, Video File Playback

Alternative downloads

VLC media player
3.0.10
FREE
Watch your favorite movies and listen to your music from one app.
Flip Player
3.3.8.1
This application lets you play videos of various formats on your Mac.
HeldenViewer
1.0.2
FREE
Search, download and view Youtube videos.