Video files consist of lots of information and data that helps to render the visuals you see into content that can be seen, edited, shared, and archived more efficiently. A key aspect to video file conversion is knowing who the audience is, and how they will be using the video file.  Bigger files are necessary for people who will be editing and calibrating videos for an editing project, in which the highest quality is needed, however smaller files are easier to share and distribute and work better for when you content is complete and ready to be seen by an audience. The process of converting and creating media depending on a process known as "encoding" and knowing this premise will help you understand which options are best for file conversions.