help with video conversion

I'm really not tech-savvy at all and reading some of the threads on here confused the hell out of me. I've converted some avi movies and a few clips off of youtube using an flv to avi converter and then the meizu conversion software. Cartoons look fine but anything with people and lots of movement looks pixelated and fuzzy. Any way to get better quality clips without overly complicated programs?

try BatMan to do it in one step.