"What did you do right before it broke?" is the question every developer asks and almost no user can answer accurately. People don't remember which button they clicked second, whether the page had finished loading, or that they hit the back button in the middle of a form. Session replay answers the question without asking it: a scrubbable recording of what actually happened in the user's browser, attached to the bug report.
How session replay actually works
Modern session replay is not video. Recording pixels would be enormous, slow, and blind to the structure of the page. Instead, tools like rrweb — the open-source engine BugDump's replay is built on — take a snapshot of the DOM and then record mutations: nodes added and removed, attribute changes, input values, scrolls, mouse movement, clicks.
Playback reconstructs the page from that data, like replaying a chess game from notation instead of filming the board. The result is compact, and because it's structural rather than visual, you can scrub through it and see exactly which element the user interacted with — not just where their cursor was on screen.
The practical consequence: replay is cheap enough to run in the background continuously, so the moments before a user decides to report a bug are already captured when they click the report button. That's the part video-style "record your screen now" flows can never give you — the bug already happened by the time anyone starts recording.
What replay tells you that logs can't
Console and network logs tell you what the code did. Replay tells you what the user did. Bugs live in the gap between those two, and some categories are nearly undiagnosable without the user's side:
Sequence bugs — the modal breaks only when opened, closed, and reopened. No single log line says that; the replay shows it in ten seconds.
Race conditions — the user clicked before a request finished. The replay timestamps the click; the network log timestamps the response; together they're the diagnosis.
"Wrong" input that isn't — the user pasted a value with a trailing space, or autofill populated a field you didn't expect. Replay shows the form's actual state.
UI state confusion — the user was on a filtered view, or a stale tab, or halfway through an unsaved edit. The DOM state at each moment is right there.
The inverse is equally true: replay without logs shows you that the page broke but not why. The uncaught exception is in the console; the 500 is in the network tab. This is why replay is most useful as one panel of a complete report rather than a standalone tool.
Replay in a bug reporting workflow
The traditional home of session replay is analytics — record everyone, then sample sessions to study UX. That model is powerful but heavy: you store thousands of sessions to occasionally look at one.
Bug reporting inverts it. BugDump collects replay in the background and attaches it when a user files a report, alongside the console buffer (up to 300 entries, 2,000 while recording), the network buffer (150 requests, 1,000 while recording, failures flagged), environment details, and performance metrics. You get replays precisely for the sessions where something went wrong and a human said so — the highest-signal sessions there are.
The report arrives as a complete case file: read the user's one-sentence description, scrub the replay to see the action, check the console for the exception it triggered, and find the failing request in the network log. For many bugs, that sequence replaces the entire "steps to reproduce" conversation.
Privacy considerations
A DOM recording can contain everything a page displays — including what users type. Take that seriously:
Decide what's recorded. Replay should be a deliberate toggle per project, not an invisible default you forgot about. BugDump exposes it as a feature flag (
features.sessionReplay) you control.Filter sensitive traffic. If you capture network data, use filters to keep third-party or sensitive endpoints out of the buffers entirely — dropped before they're stored, not redacted after.
Let reporters redact visuals. Screenshot annotation with a blur tool means a user can hide their own account number before sending. Redaction by the person who knows what's sensitive beats redaction by regex.
Disclose it. Your privacy policy should say that bug reports may include a recording of the reporter's session. Users filing a bug report are usually glad the data goes with it — but they should know.
When replay is overkill
Not every project needs replay on day one. A content site with no interactive state gets most of its value from screenshots and console logs. Replay earns its place when your app has flows — multi-step forms, editors, checkouts, dashboards — where the path matters as much as the endpoint. If your last five bug conversations included the phrase "okay, but what did you click before that?", replay pays for itself immediately.
It's also worth knowing what kind of "recording" you're getting. BugDump's widget offers both explicit screen recording (the user narrates a problem while capturing their screen) and background session replay (automatic, attached to reports). The first is a communication tool; the second is a forensic one. They complement rather than replace each other.
The bottom line
Session replay closes the oldest gap in bug reporting: the difference between what users say happened and what happened. Paired with console logs, network data, and environment details — and collected automatically at the moment a real user hits a real problem — it turns "cannot reproduce" from a resolution into a rarity.