Video start and complete events
video_start and video_complete are GA4 video events that mark the beginning and end of a video play. GA4's enhanced measurement collects them (plus video_progress) for embedded YouTube players. Together they bracket viewing: starts show interest, completes show retention, and the gap between them measures how much of your video people actually finish.
What this means
GA4's enhanced measurement includes a video-engagement option that, for embedded YouTube iframe-API players, fires video_start when playback begins, video_progress at 10%, 25%, 50%, and 75% thresholds, and video_complete at the end. Each carries parameters such as video_title, video_provider, video_url, and video_duration.
Start and complete are the two ends of the play: one shows the decision to watch, the other shows the content held attention to the finish.
Reading retention
Comparing video_complete to video_start gives a coarse completion view; adding the video_progress milestones shows where in the timeline viewers leave. A video with many starts but few completions is losing people partway — the drop-off point often pinpoints a slow intro or a topic change. Enhanced measurement covers YouTube embeds; other players generally require custom events to produce the same signals.
- video_start fires at playback begin, video_complete at the end
- video_progress milestones sit between them
- Enhanced measurement covers YouTube iframe-API embeds
How it appears in analytics and logs
A video_start means playback began; a video_complete means it reached the end. A wide gap between them means viewers abandon mid-video — the content loses them before the finish.
Diagnostic use case
Measure video interest and retention by comparing how many viewers start a video against how many complete it, isolating where they drop off.
What WebmasterID can help detect
WebmasterID can record video-engagement events first-party, so start and completion are measurable alongside page traffic without separate video-analytics tools.
Common mistakes
- Expecting these events from non-YouTube players automatically.
- Reading completes without starts (or vice versa) in isolation.
- Ignoring video_progress when locating drop-off.
Privacy and accuracy notes
These events record video identity and progress, not the viewer. Video titles and providers are content metadata, not personal data.
Related pages
- Video engagement events
Video engagement events record interaction with embedded video: video_start, video_progress (at 10/25/50/75% milestones), and video_complete. GA4's enhanced measurement captures these for supported embeds automatically. They turn an opaque 'a video exists' into a watch-depth signal — and because progress is milestone-based, you can see where viewers drop off rather than only that they pressed play.
- Enhanced measurement (auto events)
Enhanced measurement is a GA4 setting that automatically collects a set of interaction events — scrolls, outbound clicks, site search, video engagement, file downloads, and form interactions — without extra code. It is convenient but not magic: it only covers standard patterns, can over- or under-count, and each option can be toggled. This page explains what it does and its limits.
- Event parameters: adding context safely
Event parameters are the key-value details attached to an event: which button, which product, which step. They are what turns a bare event name into something analysable. The craft is choosing a small, stable set of parameters with consistent names and values — and the discipline is keeping every one of them free of personal data, because parameters are stored and widely visible in tooling.
- Event Explorer
Inspect video start and completion events.
Sources and verification notes
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.