help understanding Mp4 moov atom

[joshua4]

From what I understand,

• in MP4 files the MOOV ATOM is calculated during encoding

• for streaming video, it is best to place this at the beginning of the file called fast start

• if only part of the MP4 file is downloaded and missing the MOOV ATOM, the file is essentially unplayable

Knowing these things to be true:
How are MP4 files do NOT have the MOOV ATOM at the beginning able to be streamed? I can paste a URL into VLC and it seems to do fine.

[notaghost]

from what i know if mp4 does not have MOOV ATOM it does not play, not even with VLC you need to add it first. if VLC can play it , it could already have MOOV ATOM. (i could be wrong.)

if mp4 has fake MOOV ATOM this might help
https://stackoverflow.com/questions/18294912/ffmpeg-generate-moov-atom/31147722

[rodrigez]

If the moov atom is at the end, the file cannot be played until it is fully downloaded