Preview and the Source Monitor

The preview monitor shows the frame under the playhead. The source monitor is the same window pointed at a single media file, so you can review a source and send only the part you want to the timeline.

Play and navigate

Play and pause with the preview controls or Space.
Step one frame at a time with Left and Right.
Jump to the start with Home and to the end with End.
The timecode display shows the exact playhead position.
On a narrow monitor the controls row makes room for the play controls: the total duration hides first, then the zoom menu. Pinch and Cmd/CtrlCmd + scroll still zoom.

Frame the view

Adjust the preview zoom to inspect detail: pick a level from the zoom menu, hold Cmd (Mac) or CtrlCmd (Windows) and scroll over the monitor, or pinch on a trackpad. This never changes the export canvas.
Use Fullscreen when you are reviewing motion or framing.
Use Save frame to write the current frame out as an image.
Transform, mask, and edit overlays appear on the monitor when a matching item is selected.

Monitor volume affects what you hear while editing. It never changes the exported mix. When a clip has a proxy, playback uses the proxy for smoothness, while exports always use the original.

Video larger than 1080p gets a proxy automatically. The editor makes it in the background and pauses that work while you play, so right after an import the preview can still use the original for a moment. Filmstrips and waveforms also wait until you pause. Use Disable Proxy Playback in the preview controls to watch the original.

When a clip will not play

Some files use a format your browser cannot show, for example certain phone or camera recordings. The monitor then shows Can't play this video with the clip name, and a message names the file once. Convert it to H.264 MP4, then replace the clip to see the picture and export it.

If a clip's file on this computer was only partly saved, for example because the tab closed while it was copying, the editor downloads it again from your media library when you open the project. You don't need to do anything.

Open a source

Double-click a media card, or choose Open In Source Monitor from Media info.
The header shows the source file name, with a close control to leave it.
Source playback is independent of the timeline, so scrubbing a source never moves the timeline playhead.
Click the timecode readout to switch between timecode and frame numbers.

Mark an in/out range

Move to the first frame you want and press I (Mark In).
Move to the frame after your last wanted frame and press O (Mark Out). The out point is exclusive.
Fine-tune by dragging the in handle, the out handle, or the whole range on the strip.
Use Play In to Out to review just the range, or Alt+XOption+X to clear it and use the full source.

Choose where the edit lands

The V toggle turns the video patch target on or off. The A toggle does the same for audio.
Each toggle has a destination picker: Auto, a specific track by name, or Create on edit to make a new track.
Video with sound places a linked video and audio pair across the V and A target tracks.
The active timeline track pre-fills the matching destinations.

Insert and overwrite

Both edits place the marked range at the current playhead frame, then move the playhead to the end of the new clip.

Edit	Key	What it does
Insert	`,`	Drops the range in and pushes later material on the target tracks to the right.
Overwrite	`.`	Replaces whatever sits under the range and leaves the surrounding clips in place.

Images default to a three-second clip unless you mark a shorter range.

If an edit will not apply, enable at least one of the V or A patch targets: A for audio, V for a silent video or an image. A locked target track also blocks the edit, so unlock it and try again.