Q: How to convert video to reduce the size and keep it good quality?

A: Use Any Video Converter

http://www.any-video-converter.com/products/for_video_free/

Any Video Converter Freeware- the Free Video Converter - is the most renowned free video converter for converting video files between various formats, including AVI, MP4, WMV, MKV, MPEG, FLV, SWF, 3GP , DVD, WebM , MP3, etc for iPad, iPod, iPhone, Android, PSP, Tablets.