Help
Troubleshooting
FirstCut runs entirely in your browser and plays your cut back from the original video files on your own disk — so most snags come down to playback, relinking, or which browser you're on. Here are the usual ones.
Playback
Why do I see a black video in the player?
A black frame almost always means one of two things: the source file isn't linked correctly, so the player has nothing to show, or the video is in a format your browser can't decode. Remember that only the audio is uploaded — the picture is played straight from the original file on your disk, so both the link and the format have to be right for you to see anything.
Fix: first, relink the footage and make sure you're pointing at the exact source file — this clears up most black-frame cases. If it's still black after relinking, the format likely can't be decoded in-browser: transcode the source to a standard, widely-supported format (H.264 .mp4), re-import, and relink. For the full details, see Relinking footage and which formats are supported below.
My cut won't play (black frame, or it skips clips)
FirstCut only extracts and uploads the audio from your footage — the video itself never leaves your machine. To preview a cut, your browser has to decode the original video file, and some camera formats can't be decoded in-browser: ProRes .mov, many .mkv files, and some HEVC/H.265 clips. The transcript and edit still work perfectly — only the picture preview is affected.
Fix: transcode the source to H.264 .mp4 (any editor or HandBrake will do it), re-import, and relink. The cut timing is unchanged — you're only swapping in a decodable file.
Clip boundaries look slightly off
The player is a preview, not a frame-accurate NLE. Clip boundaries advance on the browser's timeupdate event (~250 ms granularity) and switches between two different source files aren't gapless. Your exported EDL/XML carries the exact timecodes — the drift is in the preview only.
Fix: trust the export. Open it in Premiere, Resolve, or Final Cut for frame-accurate cuts.
Relinking footage
It keeps asking me to relink my footage
Because your videos live only on your disk, FirstCut has to be pointed at the files each time it can't remember them. Within a session, links are held in memory and survive navigation. Across sessions, it can only re-grant access to files you linked before on a supported browser (see below).
Fix: use Link from folder to point at the whole footage folder once — every matching source relinks at once. Or drag a file straight onto the player frame to relink just that clip.
“Restore footage” doesn't work / never appears
Remembering footage between sessions uses the browser's File System Access API, which is Chromium-only (Chrome, Edge, Arc, Brave) and needs a secure context (localhost or an HTTPS site). On Safari, Firefox, and most mobile browsers there's no persistent handle — you relink per session with the file picker. Re-granting also requires a click (browsers won't restore access silently).
Fix: for footage that persists between visits, use a Chromium browser on desktop. Everywhere else, relinking each session is expected — nothing is broken.
Import & generation
A file wouldn't import
FirstCut reads AAC audio out of any browser-readable container (MP4/MOV/WebM/MKV). If a file has non-AAC audio (Opus, AC-3, MP3) or no audio track, you'll be offered to upload the full video so the server can extract it instead, or to skip it. A truly unreadable file is rejected.
Fix: take the “upload the full video” fallback when offered, or convert the file to an MP4 with an AAC track and re-import.
Generation seems stuck
Transcription and the edit run in the background — the page waits on a live update from the server, so a slow model or a large batch of footage can take a while. The progress bar is paced from your own past runs and deliberately never claims it's done early.
Fix: give it a few minutes. If it never advances or shows an error, reload the Sequence — the live document will reattach. Persistent failures usually mean a source never finished transcribing; check its status in Media.
Still stuck?
If none of the above fits, note which browser and OS you're on and what the source format is — those three facts explain most playback and relink issues. See also the privacy summary for exactly what does and doesn't leave your machine.