Verify a large video download beyond the browser progress indicator

A download that appears to finish is not necessarily the complete accepted artifact. Interrupted connections, resumptions and changed representations can leave a file that opens at the beginning but is incomplete later.

Make the decision explicit

Retain the expected byte length and an independently recorded digest for the accepted output. After downloading, compare the complete file, not only the first playable seconds. If resuming a transfer, verify that the server returns the expected range behavior and that the representation has not changed before appending bytes.

A worked example

Consider an invented 180 MB delivery interrupted after 40 MB. A later request may return a partial response or the entire representation, depending on the request and server behavior. Blindly appending a full response to the partial file produces an invalid combination. The correct decision follows status, range metadata and representation identity rather than a filename that happens to match.

Review before handoff

Test playback near the end as well as at the beginning. A matching digest checks byte identity against the retained expected value; it does not verify the film's facts, rights or sound quality. Keep those editorial reviews distinct. A file-size calculator can help estimate expected scale, but only the actual artifact record can identify the exact delivered bytes.

Put the idea to work

Read http range request and use the related free workflow tool for its stated, limited task. Neither link replaces the review described above.

Reference and editorial notes

• MDN: HTTP range requests

References checked October 29, 2026. Numerical and fictional scenarios are illustrative unless explicitly identified otherwise. The cover is an original Topicut explanatory diagram, not a product screenshot or a measurement.