It could be downloaded via torrent.
Is it legal if someone will distribute a prebuilt of UE4 ?
The build is not stable enough at this time, so it makes sense to not make it readily available to people that aren’t going to be able to help troubleshoot issues as well as those compiling it from source.
I don’t think it’s a good idea to redistribute builds at this point, because the end-users won’t be able to provide any details about the build specifics if they need to report issues.
If you are using torrent, then you redistribute the file. We can’t redistribute UE4 according to EULA.
Last time I talked to about this, I came away with an understanding that basically boils down to, There is a LOT of work that needs to be done to provide an official Unreal Editor build, That costs money, time, personnel etc. and at the moment, There has been little to show for how epic games would be able to recoup the significant investment it would take to complete. Especially since it is an ongoing investment, as stuff has a habit of breaking in weird ways throughout various updates. (I believe both OS and editor updates), If I remember correctly, depending on how well Vulkan does, it may be looked at again.
Please note, These are the impressions and opinions are mine, not epic or Tim.