"This video is not available in your country due to copyright restrictions"

Why???
There are a few reasons why you'd see the message "This
video is not available in your country" or "We are unable to
show you the original featured video for this channel due to
age or location restrictions":
Although each country has its own copyright laws, several
nations have bilateral or reciprocal agreements with others
such that the rules that apply in one country are enforcible
in the other. Some countries also have commonality in the
copyright laws. The EU and the part of NAFTA concerning
"culture" are good examples of this.
Then, there are questions of international dispute, such as
China refusing to abide by anybody's copyright laws. Thus
copyright holders/owners often place restrictions on where
their videos can play and where they can't.
Then, there are issues related to "licensing". Broadcasting
companies such as ABC, NBC, MTV, BBC and others are
international with subsidiaries or affiliates around the world
which they do not want to infringe on. The opposite is also
true: they might not be concerned about their videos being
watched internationally but are weary of what's available in
their own country, usually due to licensing fees & royalties.
Thus it happens rather often that an MTV video is playable
in the US, but isn't available at all in Canada. The opposite
is also true: ABC videos are common in Canada but not in
the US itself. Same goes for the BBC: Canada yes, UK no.
And then there's the "Performing Rights Society in the UK
(otherwise known as "PRS for Music"). They are presently
negotiating with Google/YouTube over music videos.
As such, trying to change your "country" in YouTube's set
of options won't help you in being able to see videos which
are "not available in your country".
1 -- Choosing another country or Worldwide (All) at the top
left of a YouTube page only changes the way YouTube will
display itself to you, such as it's homepage -- nothing else.
2 -- Changing the country on your profile/channel page will
only change the country people see in your profile.
3 -- Creating a brand new YouTube account (and choosing
a different country) would also have no real effect, because
YouTube already knows which country you're in, based on
the IP of your computer & the previous time you registered.
4 -- Even if you created a new account on a new computer,
YouTube may still know which country you're in, based on
the known address of your ISP.
Sorry, but as far as I know, videos which are "not available
in your country" cannot be seen.