An SRT file contains the dialog and timing information used to display subtitles on your media player. SRT subtitles are often used with movies encoded with an AVI container such as H.264 or DivX. In ...

A caption file is a completely separate file from a video file. Caption files can be made in a wide variety of formats, and you can upload a caption file to accompany a video in order to create closed ...

That being said, Twitter can reject your file with a less-than-helpful message of: "There was a problem uploading your subtitle (.srt) file." So it's important, at least when you first start, to ...