Media diagnostics · Primary-source explanation; examples are illustrative. Instructions are based on publisher guidance; a UK IPTV account was not tested on this platform.
Use hidden for processing without display
A developer building a transcript search may need timed cues without overlaying subtitles on the video. TextTrack mode provides a specific distinction: hidden keeps the track active and maintains active cues without displaying them, while showing presents the track. Disabled is different again. MDN explains that a disabled track is ignored and its cues may not be obtained until the mode changes. Hiding captions with CSS is therefore not the same operation as selecting a track mode.
Diagnose an empty cue list carefully
For an illustrative local test, a permitted WebVTT file contains two known lines. The page sees the track object but its cue list is not yet populated. Before concluding that parsing failed, inspect the mode and resource request. Change to hidden when the application needs cue processing, then wait for the appropriate loading result. A missing list at initial page load is not sufficient evidence that the file contains no subtitles.
Keep purpose and viewer controls aligned
If the viewer asks to see captions, showing is the relevant state; hidden will deliberately keep text off screen. If the application merely needs a searchable transcript, hidden can serve that different purpose without unexpectedly covering the picture. Check actual behaviour in the supported browser, including the custom control requirements documented for Safari. This explains track loading and visibility, and does not promise that a programme has an accessible caption track in the first place.