Almost all video is in a "lossy" encoding. To convert it to another encoding you would decode it and re-encode using another lossy encoder. Something is always going to be lost.
How to convert my videos without loosing quality? I tried with super converter http://www.softspecialist.com/Super-Converter-4267/Super-Converter.htm but I couldn't figure it out. I'm thinking it is due to my lack of knowledge and I need some help.