well at least we know the branch that the preview updates will be coming from (fbl_release) is building daily.
Currently there are 3 branches that have active preview builds: fbl_release, winmain, winmain_prs Enterprise edition has one more: fbl_kpg
There are plenty of active branches as listed on that betawiki page what i ment is that for us regular users, only some branches could give you "Download new preview build" in PC Settings other would give "No new preview build was found, please try again later"
almost all the info can be found in view of the EventViewer ... besides 9855 is old... 9857 is the newer
I did a quick bit of digging using Process Monitor. By the looks of it when the download it initiated it queries another registry key HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Flighting\Build and then from within that a sub key named UpdateID which at a guess would possibly contain information regarding the downloaded build. The download also kicks off an https request to MSFT which can be seen from the output.
Why do I have the feeling that Microsoft is showing us more than they intended? They are giving us incredible insight to their build strings and how to exploit them in future technical preview cycles.
Then why there is such rumor that there are actually newer preview builds if nobody downloaded them? And also why the registry hack to download these builds?
The builds ain't rumours as you can see them in Event log after download failed . Question is what conditions allow to download them.
These updates that we've logged use the Windows Store infrastructure. This poses a difficulty for those trying to break into it because obviously there's a lot tighter checks and many more layers of protection with the Windows Store. It doesn't just hand out data, you need a cryptographically-signed and encrypted authentication ticket that expires within a certain period in order to download anything successfully. Basically, I'd consider it highly unlikely for any of these builds to get out. That said, interestingly, the Windows 7 TP upgrader uses the traditional Windows Update which is not secured in any meaningful way, so if a build were to pop up on here, we'd definitely be able to grab it. My guess though, is that this will only be reserved for public builds anyway. Still, it's fun to see all these fbl lab names. fbl_mobs and fbl_lad are my favourite two so far.
Probably the same condition which does let you name your computer MS gives every install its own name.