Follow the steps below to convert WMV files to MPEG.
Converting WMV to MPEG using Mopal Video Converter
http://www.softe.net/video_converter.php
1. After launch Mopal Video Converter, In the folders pane, click on
the folder contains WMV files you want to convert to MPEG.
2. In the file list pane, select one or more WMV files.
3. Right click on the selected WMV files to bring up the context menu
and select Convert.
4. In the Video Format Conversion window, select MPEG-1 or MPEG-2 from
the Output->Format list.
5. If you want to change the output quality, select the video/audio
combobox. (optional)
6. If you want to change the destination folder for MPEG, click on the
Browse icon button to change. (optional)
7. Click Convert to start converting.
http://www.softe.net/mopal_help/convert-wmv-mpeg.php