The image must contain valid EXIF data, and frames extracted from video don't AFAIK. Why aren't you using one of the numerous camera apps which should capture valid still frames?
I don't -- I don't have or use any smart phone, but I know lots of people take pictures with them. Maybe look up someone on the list of users here an PM them?
I am sure a photo I recently entered that came 4th was validated and I had an associated jpg image and this photo is appearing on my iPhone as Live. All I do is copy my photos to Dropbox and then upload from PC to DPC