Amazon Instant encv/enca

[blimey]

I've noticed that Amazon Instant flash streaming for paid programs (as opposed to free or prime program streaming) is encoded differently than the free/prime streaming.

Free/prime are encoded using the common avc1/mp4a for the video codec id/audio codec id.

While paid programs are encoded using encv/enca for the video codec id/audio codec id.

I don't know what is encv/enca, as found in a flash container. Except that the resulting file won't play and seems encrypted. The MP4 does mention encryption, but is this beyond the usual flash tricks, how does the flash player handle it? Does anyone else know?