I don't see any reason why it will not download. You are set to default to 720p and EC3. Both are available as shown below. 
I see nothing unusual in your log other than your back and forth between 6.1.5.7 and 6.1.6.0. Forget about 6.1.5.7. I can not help you with anything but the latest version.
My suggestion is to do a clean installation of the latest StreamFab release, meaning use a "professional Uninstaller" such as Revo, Ashampoo, and many others (Google "Uninstallers" for additional free and pay programs) to uninstall SF. Right now, I prefer the Ashampoo - . Revo sometimes makes you reboot your computer.
1) Delete your StreamFab Log and Temp folders.
2) Run your uninstaller and remove the existing StreamFab including the registry entries. At one point, it will ask you if you want to save your StreamFab configuration. Say NO. A StreamFab window will come up and ask why you are uninstalling, choose Other and type Clean Install.
3) Start reinstall using latest offline update file. I prefer to get mine from the Sticky at the top of this forum.
4) A StreamFab popup will ask for your email/password to authorize your StreamFab. Give your DVDFab email/password, not your forum email/password, if different.
5) Ignore all the garbage advertisements. I don't think I have to tell you that.
6) Reset up your Settings and the GUI the way you want it to look.
7) It is always best to close and then open StreamFab at this point.
8) Give StreamFab a try.
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