All Naruto episodes after 54 are encoded in H.264, So You Should Download A New Media Player Such as VLC (Availible Here.) or Download the Correct Codecs.
Avatar Book 3 Chapter: 18-21 (HD- Quality) and Naruto Shippuuden 91-Current are Encoded in MKV. To Play them Using Windows Media Player Grab CCCP codec Pack Below. To Play the MKV files on a Mac (OS X) Download VLC Player For Mac Below.
DECOMPRESSION PROGRAMS FOR WINDOWS~~~~~~~~~~
WinRAR-Download (Needed To Extract RAR, part1, and part2 Files)
CODECS FOR WINDOWS~~~~~~~~~~
FFDshow-Download (Needed to Play Most AVI files)
Combined Community Codec Pack (CCCP)*Reccomended* Download
(Needed to Play MKV Files and Some AVI files)
PLAYERS FOR WINDOWS~~~~~~~~~~
VLC Player- Download
Media Player Classic- Download
DECOMPRESSION PROGRAMS FOR MAC~~~~~~~~~~
UnRarX-Download (Needed To Extract RAR, part1, and part2 Files)
CODECS FOR MAC~~~~~~~~~~~~~~
3ivx (Quicktime Needed)-Download
PLAYERS FOR MAC~~~~~~~~~~~~~
Quicktime (Needed to Play AVI Files With 3ivx Codec)
-Leopard- Download
-Tiger- Download
-Panther- Download
VLC Player (Needed to Play MKV Files)
-OS X(Leopard, Tiger, and Panther) Download