Ok, I finally got around to trying this out.
I was afraid of getting a developer key on the google account that my main youtube channel is tied to - because it required me to fill in false information - so I made a new google account. Sadly, the developer key I got only works for said google account and I wasn't able to get any keys from my other two google accounts, since this page
https://code.google.com/apis/youtube/dashboard/gwt/index.html#newProduct
would appear simply blank since then.
So I had to open a new youtube account.
Aside from these troubles, I was able to upload a test video just fine and am going to upload an actual file now.
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EDIT:
My upload failed at 15%.
http://i.imgur.com/f9nLn.png
It might be worth noting that Chrome, when I had tried it, always froze halfway through the upload - most likely due to my ip changing, but I don't know if it can be related to YTU...
The highest progress I got in Chrome was 70%. I might as well just try until it's up - though it takes over 20 hours to get anywhere...