Live mic
A speaker in the room — lecture, discourse, any audio you can hear. Earbuds for the translated voice.
File
An audio/video file on the phone — plays and translates from its own audio. No mic, no echo.
Link
A direct media link (.mp3 / .mp4 / .m3u8).
YouTube/OTT page links can't be captured on one phone (iOS forbids it; Android blocks DRM audio). Download the video and use the File tab, or use YouTube's CC ▸ Auto-translate for text. File & Link use the Sarvam engine.