The export is a bundle of choices.
Media exports combine dimensions, frame or sample rate, codec, bitrate and duration. File size is the result of those choices, not one magic quality switch.
Video & GIF
Convert subtitle files.
Turn SRT captions into WebVTT, or WebVTT back into SRT. If nobody specifically asked for VTT, SRT is usually the more common starting point.
Subtitle text
Preview
WEBVTT 1 00:00:00.000 --> 00:00:03.000 Hello from OutMonkey.
Useful to know
Four things worth knowing.
Exporting is not mastering.
A browser utility is good for a focused conversion or edit, but it is not colour grading, audio mastering, motion tracking or a full timeline.
Play the whole thing.
Play the exported file from beginning to end and check picture, sound, crop, timing and orientation.
Match the destination.
Play the export all the way through once. Broken audio, a bad final frame or a mistimed subtitle often hides near the end.