To: defreeman
Are FLV files played back when you preview them in AVS Video Converter or AVS Video Editor? Try to play them up to the end.
If they are played fine, but still cannot be converted, make sure you have enough space on your hard disc for saving the converted files. Also attach the screenshot showing all the input and output settings: open one of the files in AVS Video Converter, choose the preset, then click on Advanced > File Information and make a screenshot.
Thank you