Videos won't play - Apple iPad Mini

If the video or audio files added to the device do not play well, it can be due to either of the reasons below.
1. The file size is too large and the device needs to take some time to read and play it.
2. The file on the device is damaged, protected or unauthorized. Please first confirm that the original file plays well on the computer and is not protected.
If you have confirmed that the original file plays well on the computer and is not protected, please contact us with the source video or audio file.
You can check on this tutorial to see how to solve this kind of problem:
How to Watch WebM on iPad

Update the media player to the newest version.
When media players go through upgrades, new codecs are often added to the player along with new features.
These new codecs give the player an ability to play videos in additional formats.
Download and install a codec pack for your computer-based media player from a codec website, like Free-Codecs.

See Below
http://www.free-codecs.com/download/k_lite_codec_pack.htm
The K-Lite Codec Pack, for instance, contains multiple codecs and works with multiple media players, which gives all of the media players that are installed on your system the capability to play any video file that uses those codecs.
Once you download a codec pack, go to the "Downloads" folder on your computer, right-click the codec pack and choose "Extract All" to extract the codecs and move the codecs into a folder on your "C:" drive.
The codecs integrate into your computer-based media players automatically.


Get a new player. If you have updated your player and installed all of the available codecs, and video still won't play in the player, the player may just not have the necessary components to play your video files.
Download and install a new player, such as Winamp or the VLC Player, to your system.
http://www.real.com/realplayer

http://download.cnet.com/Winamp/3000-2141_4-10251792.html
http://www.videolan.org/vlc/
Personal Media Players
Find out which video formats your media player accepts.
This information should be provided in the user's guide that came with your player. iPod, for instance, accepts video only in the M4V, MP4 and MOV formats, according to the Apple website.


Convert the video file to a format supported by your personal media player in an online conversion system.
Some online systems that can make video conversions include Movavi Online Convert and YouConvertIt.


Remove the original video file from the media player using the player's software, such as iTunes for iPod devices.
Then, add the new video file to the software library and drag the new file to the device.
Once the video is in the correct format, the codecs in the media player should read the converted video file.