Video cover capture — technique benchmark

Runs three capture techniques against the same video and the same timestamp, so they can be compared on time, bytes and output rather than argued about. Run it in every browser you support — Chrome, Firefox, Safari, and a real iPhone.

Cache caveat for manual runs. Techniques run in sequence in one page, so the second and third benefit from bytes the first already pulled. Press Run (cold) to append a cache-busting parameter per technique, which is the fair comparison. The Playwright driver runs each in a fresh browser context and needs no such trick.