video question

Ok, new here...Samsung Galaxy S Vibrant....Somehow a couple of vids got .txt behind the name of the videos and are unplayable. How do I take the .txt from the back of the name of the video so they can be played. CAN'T rename, it says the files already exist.:thinking::thinking::thinking::thinking:
Videos from the stock camcorder? Or videos you put on manually?

Either way, just connect the phone to your computer with the usb cable, find the files, and rename them.