Most recent video players are capable of playing the different formats proposed on this site. If you are having problems with your favourite player, try downloading the most recent update or consult the respective sites for these players.

Common video players - downloads

Recommendations for video formats
WindowsMedia (.wmv)
Use Windows Media Player

RealMedia stream (.rm)
Use RealPlayer®

DivX (divx.avi)
Use recent versions of the common players listed above or the free DivX player on divx.com