Don’t render an animation in one step as a movie file. That could cause problems because sometimes Blender creates corrupt movie files or the movie player can’t read the files!
Step 1: Render the animation as single images (png-files) with Ctrl+F12 (not as a movie-file) and save the images in a sperate folder (in “Render settings” -> “Output”. If you render with Ctrl+12 Blender will render one frame after another and saves the single images automaticlly in the selected folder.
Step 2: After rendering all images, go to the video sequence editor, select “ADD” -> “Images” in the menu and select all images files in your folder (A) where you have saved the images.
Step 3: After loading the images in the video sequence editor you see the image strip that “contains” all selected images. Go to the render settings
-> “output” and select “file format” -> H.264 and
-> “Encoding” -> “Format” -> “MOV” (or any other movie format)
optional settings: “Bitrate” : 14.000 and “Maximum”: 14.000
Step 4: Press Ctrl+F12
Blender now uses the single images in the image strip and renders the animation. That will only take a few seconds.
I do all animations in this way and have no problems with the movie files.
Hope this helps.