Pheran said:

The AVCHD format is mainly intended for folks (like myself) who don't yet own Blu-ray burners. The movie is still encoded in HD format, but it will be no larger than 8.5G so that it will fit onto a dual-layer DVD. You can then burn it to a DVD that you can play in a regular Blu-ray player.

If you do have a Blu-ray burner, then you can probably just burn some variant of the existing MKV.

Thanks for that explanation: I was wondering why anyone would want to compress the video further by 50% because the final quality has to be compromised in some way (unless the original video has not been compressed by much).

For those with Bluray players that can handle mkv on a usb drive, then the mkv will be the highest quality one to use.

Maybe we can convince Harmy to release the eventual Bluray as a series of mkv too, for those without Bluray burners but who have mkv capability.