The most used file formats are
FLV or Flash video – It is the most popular format due to flash player plug-in is installed on most computers. Creating video needs the flash authoring software which can also create video players for playback thus facilitating in control of look and feel of the player. It uses flv or swf file extension and it has good compression and thus lower files size.
MPEG It is a video format developed by the Motion Picture Experts Group (MPEG). Most computers have a windows media player or quicktime player which plays MPEG video format files. It has mpg file extension and its file size is larger than flash.
WMV or Windows Media Video It requires windows media player to play it and has wmv file extension.
MOV files are based on quicktime movie file format which can have file extension of MP4 or mov and has small file size.
AVI (audio/video interleaved) It is known as a container format as in it video is compressed with another codec thus some AVI files may play, and not others. Its file extension is avi.
RealVideo It was the first video formats used for showing video online. Its file extension is rm.
Flash Video is the most popular video on the web.