When i use nextgen gallery for my customer site, i can't not upload image with flash uploader. After debugging 1 day, i try to do use the lastest version of 2 files: "swfupload.js" and "handler.js" and replace 2 files in nextgen "swfupload.js" and "swfupload.handler.js".
Luckyly, I work for me. Thank god.