The video is uploaded to rupload.facebook.com/messenger_video/<uuid> through
MessengerMediaUpload, the one owner of a media upload's wire (the header set
the foreign host needs, the upload slot, the entity headers and the owner's
error mapping). The video's own segment and waterfall params ride with it as
entity params; the segment offset rides only on the file's POST, as the app
sends it.
Send new video from a gallery.
The video is uploaded to
rupload.facebook.com/messenger_video/<uuid>throughMessengerMediaUpload, the one owner of a media upload's wire (the header set the foreign host needs, the upload slot, the entity headers and the owner's error mapping). The video's own segment and waterfall params ride with it as entity params; the segment offset rides only on the file'sPOST, as the app sends it.