[Nawid3333]

What changes for the user

• An MP4 file the MP4 player cannot read (a file mp4box cannot parse, a codec MSE refuses) is played once in Firefox's own player inside FastStream (the existing playDirectly hand-over, at the time it was at), once the next source and a rebuild are no way out, instead of the load error. FastStream's player and its controls stay; nothing of the page comes back by itself.
• The load error now says how to watch the video in the site's own player, in a page: "Turn FastStream off with its toolbar button to watch it in the site's own player." It is the DRM error's own second sentence, reused in every locale (player_error_turn_off). A player in a tab of its own shows the error alone.

What does not change

• A refused request (isNetworkFailure: a range or the first fragment that failed to load) still shows the error: Firefox's own player would send the same request, and the page's new link may be on its way (renewSourceLink, Some recommandations #592).
• A video that has shown a picture is rebuilt first (recoverPlayer), as before; only when its rebuilds are used up does Firefox's own player take over, where the load error showed before.
• FastStream never steps aside by itself: a version that gave the page its player back was built and dropped unmerged on the owner's word; the toolbar's Off is the user's.

Review

glm's review: the first version tried Firefox's own player only before the first picture, by comparing identifiers, which two episodes at the same URL path share - fixed by dropping that test (the rebuild comes first anyway). Its other findings were checked and are not real: Firefox's own player keeps the page's headers since #607 (the review read an outdated fact), and the stall watchdog fires only after a picture (readyState ≥ 2).

Tests

• Unit: the MP4 goes to Firefox's own player; a refused range does not; a video that showed a picture is rebuilt first and goes to Firefox's own player once rebuilds are no way out; the error when Firefox's player was tried already; the hint only in a page. Each condition was removed once and its test failed.
• Local: lint, tsc, 3373 unit tests; e2e ext specs mislabelled-file, fresh-link, header-rules, redirected-source, source-length, same-video-file, framed-player, extension; web specs mp4-without-ranges, mp4-files, mp4-loading, player-recovery, seek-downloads, loader-retry, dash-broken-segment.

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