Windows Media Video is the current Microsoft streaming file format that replaces the legacy ASF files. WMV files can be streamed or played locally from the hard disk.
WMV can produce very small file sizes and if the videos contain real world photography, dithering or gradient fills, the file size may be significantly smaller than TSCC-encoded AVI files.

* As you can read at our FAQ page, WMV format is currently supported by Wiagra Easy Video Joiner tool, which is part of Wiagra Video Joiner installation. You can find that tool in "Programs/Wiagra/Wiagra Video Joiner/Easy Joiners" submenu of your Windows' Start menu.