WonderFox HD Video Converter Factory Pro is an excellent tool to reduce video file size. It supports virtually all video & audio files and can convert files to MP4, MKV, AVI, MOV, WMV, FLV, MPG, etc. Its built-in video editor enables you to cut/crop/split/merge videos. And you're able to change video resolution, bit rate, frame rate and more other parameters. What's more, the advanced Compression mode lets you compress large videos in one click. Now follow this instruction of compressing videos for YouTube.