Both languages on screen, matched sentence by sentence — including in Safari on iPhone.
Install a browser extension that draws its own subtitle overlay on top of the video. BelliedMonkey Translator shows the original caption line on top and the translation directly underneath, matched sentence by sentence. It runs in Safari on iPhone, iPad and Mac, and in Chrome and Firefox on the desktop. YouTube's own settings only let you pick one subtitle track at a time, so a second line has to come from an extension.
They translate each caption cue on its own. A caption cue is a timing unit, not a sentence — it often cuts a clause in half, so the translator never sees a complete thought and produces fragments that do not join up. BelliedMonkey Translator fetches the whole transcript first, merges the cues back into sentences, and translates those. What you read is a sentence pair, not two half-sentences.
No. Translation runs ahead of playback in a sixty-second sliding window, so the lines for what you are about to hear are already finished. There is a short wait when a video first loads while the transcript is fetched and the first window is translated; after that, steady playback does not go back to a waiting state.
Yes, in Safari on iPhone and iPad, which is unusual — most dual-subtitle extensions are desktop-only because the technique they use to capture YouTube's caption data is not available on mobile Safari. BelliedMonkey Translator gets the caption track a different way that works there. You install it from the App Store and switch it on once in Settings.
You get a one-line notice saying subtitles are unavailable for that video. It deliberately does not fall back to transcribing the audio or to translating word by word — a fabricated subtitle track that drifts out of sync is worse than an honest blank, because you cannot tell when it is wrong.
Yes. Beyond YouTube, video posts and podcast pages elsewhere on the web get the same treatment, and ordinary web pages get bilingual paragraphs — the original text stays in place with the translation directly below it. The subtitle overlay and the page translation are the same engine applied to two kinds of text.
A free channel works immediately with no setup and no account. If you want higher quality you can enter the key for your own AI service, or the address of any compatible endpoint, and translation goes straight from your browser to that provider. The extension itself is free and open source, and there is no server of ours in the translation path.
Already installed? Turn it on →See also: translating web pages in Safari on iPhone ·