For Internet explorer Browser: If you are using internet explorer browser, watch full video from facebook,
1. After watching full video, go at Tools> internet options> settings> view files
2 You will get a large size file with long name and unknown type there.
3 Copy and paste that file at desktop, this file is the video file in flv format
4 Rename it with flv extension, example 123.flv
5 play and enjoy video at your PC with flv player