Idx Video File [upd]

00:04:24,000 --> 00:04:24,500 Don't look at the mirror. Look at the index.

And behind Leo, in the real world, something that had been waiting for six months—patient, hungry, hidden inside a few wasted kilobytes—finally found the door. It reached out of the file, through the index, and tapped him once on the shoulder.

Since an IDX file is just a reference, you don't "play" it. Instead, you open the associated video file using a media player that supports the . How to Open, Edit, & Convert IDX Files on a Computer

It contains metadata about where the text should be placed on the screen.