WinUHA is the best for compress files not bigger than 2 GB, or 7zip (no size limit) compression Ultra or WinRAR, this are the only option to no lose quality, useful for store/back-up or transport the file on a USB or send it by internet, but you will need to decompress before watching it. Because every time you codify a video with any video format (codec) you always lose quality, more with some video formats (codecs) than with others. Anyway some of the the video formats with high compression and low quality lose (known as lost less) are H264, H265, MP4, MKV, etc., See this page for several options of free transcoders: https://www.videohelp.com/software/sections/video-encoders-h264-vc1 And to play almost any format of video you can use VLC Media Player. taviruni