Good open source player, whose main feature is not needing codecs (they are all integrated in the program). This makes it very popular, so as to place at the top of the category of player for divx, thanks to the fact that works well with DVDs. Supports DivX, XviD, AVI, MKV, MP3, VCD, DVD, OGG, OGM, MPEG-1, mpeg-2, MPEG-4, subtitles in many formats (VobSub, SubRip, DVD Micro, SSA, etc.).. No need to download additional codecs for it to work, everything is integrated.
VLC is improved from version to version, from 0.8.4 and I consider him one of the best players ever. Remains the limit of aspect ratio (only 4:3, 16:9, 221:100): From this point of view, Core Media Player, or even the old PowerDivx, are superior, offering a greater variety of formats: if the your video is not one of these formats, you probably will see their faces slightly elongated or squashed.
And good zoom function (not as advanced as in BSPlayer), where with one click you can zoom in, going to cut the edges in order to better fill the screen (recommended only for those small monitors, cut a part of the frame for greater visual area is never a good thing).
With VLC you can also see video part, or in writing those other programs (for example, can be previewed in emule). Natively supports x.264 format (H.264).
