From Media Player Codec Pack:
Media Player Codec Pack Plus is a collection of codecs, filters, or splitters used for playing back video and audio files. After installation you will be able to play files through your media player. Additional file associations are applied to make Windows Media Player play BDMV (unencrypted BluRay or AVCHD), EVO (unencrypted HD-DVD), MKV, M2TS, MP4, VOB, OGM, WEBM, FLV, and NUV movie files, as well as AC3, DTS, FLAC, APE, OGG, WV, TTA, OFR, SHN music files, and finally MO3, IT, XM, S3M, MTM, MOD, and UMX tracker audio files. Compression types supported include AVC, H.264, x264, H.263, H.261, DivX, XviD, Flash Video, VP3-8, Morgan JPEG, MJPEG, MPEG4, MPEG2.