I haven't read 'Living Buddha, Living Christ' by Thich Nhat Hanh, so I can't comment on that.
I skimmed thorugh the article 'Was Jesus a Buddhist?'. I would like to propose a few counterexamples.
The article claims that Jesus' time in Kashmir coincides exactly with his 'lost years' in the Gospels, and mentions a king:
At the age of twenty-nine he left India and eventually reappeared in Judea to begin his ministry. His time in Kashmir coincides exactly with his "lost years" in the gospels. [...] The Kashmiri Hindu text "Bhavishya Maha Purana" speaks about king Shalivahana (circa AD 80) meeting a foreigner calling himself Ishvara Putaram (Son of God).
Now suppose that Jesus did go to Kashmir during his 'lost years'. Then Jesus would've gone to Kashmir before he started his ministry:
Scholars generally estimate that the ministry of Jesus began around 27-29 AD and lasted one to three years.
Compare with this:
Gautamiputra Satakarni (Telugu: గౌతమిపుత్ర శాతకర్ణి, Marathi: गौतमीपुत्र सातकर्णि; also known as Shalivahana) (c. 78–102 CE) was the twenty-third ruler of the Satavahana Empire.
As you would know, CE is an alternative term for AD. Now, if we take it that Jesus was in Kashmir before 27 AD, and that Shalivahana was born in 78 AD, they could not have met during the 'lost years', since Shalivahana wasn't around before 27 AD. Therefore, this is a contradiction.
On a side note, suppose we take it for a fact that Peter was the first one to call Jesus as the Son of God, as revelead by God The Father:
Now when Jesus came into the district of Caesare′a Philippi, he asked his disciples, “Who do men say that the Son of man is?” And they said, “Some say John the Baptist, others say Eli′jah, and others Jeremiah or one of the prophets.” 15 He said to them, “But who do you say that I am?” Simon Peter replied, “You are the Christ, the Son of the living God.” And Jesus answered him, “Blessed are you, Simon Bar-Jona! For flesh and blood has not revealed this to you, but my Father who is in heaven. (Matthew 16:13-17, RSV)
Then it does not make any sense for Shalivahana to be the first one to have called Jesus as the Son of God during the lost years. Then again, he couldn't, anyway, as he wasn't around at the time.
Taking one example, the article claims a similarity between Jesus and the Buddha:
Born as an incarnate god.
... the Buddha himself denied that he was either a man or a god...
Note also that the article is confusing. At some parts of the article the author tries to assert that Jesus was, to an extent, a Buddhist. Then the author seems to imply that the figure of Jesus was taken from the figure of Buddha by listing the similarities between them.
Take a look at this urban legend, see here for more. So much for the sake of making something 'similar'.
I haven't watched the whole movie 'The Man from Earth'. I did watch the excerpt you gave me, however.
I looked on Google to see if I could find a source for the statements made about Moses that are said in the excerpt, but I did not find one. I found a transcript for the movie (I do not know if it is complete or not), to look up the spelling of 'Misis'. Googling for 'misis syria', I could not find anything that is specific to it. The articles that I did read, that contain the name 'Misis' does not have any citations either, they aren't credible. So for now, I can safely say that that is just an assertion without anything to back them up. Do tell me if you find some. I have not searched for evidence for the other statements. I don't think it is a good use of time anyway. Here is why.
The plot summary from IMDB for 'The Man from Earth' is as follows:
An impromptu goodbye party for Professor John Oldman becomes a mysterious interrogation after the retiring scholar reveals to his colleagues he never ages and has walked the earth for 14,000 years. Written by Eric D. Wilkinson
And, if you look at the site, the genre of the movie is 'Drama' and 'Sci-Fi'. Obviously, this movie is fiction, so you probably shouldn't take it seriously.
Compare with the movie 'Prometheus', which are classified as 'Adventure', 'Mystery', and 'Sci-Fi'. The following is an extract of the interview with the director Ridley Scott, where 'RS' stands for Ridley Scott.
Movies.com: You throw religion and spirituality into the equation for Prometheus, though, and it almost acts as a hand grenade. We had heard it was scripted that the Engineers were targeting our planet for destruction because we had crucified one of their representatives, and that Jesus Christ might have been an alien. Was that ever considered?
RS: We definitely did, and then we thought it was a little too on the nose. But if you look at it as an “our children are misbehaving down there” scenario, there are moments where it looks like we’ve gone out of control, running around with armor and skirts, which of course would be the Roman Empire. And they were given a long run. A thousand years before their disintegration actually started to happen. And you can say, “Lets’ send down one more of our emissaries to see if he can stop it. Guess what? They crucified him."
As a fan of the 'Alien' franchise, and as someone who is interested in Christianity, I find the idea captivating. However, in the end, it's just fiction.
So, no matter how fascinating or thought-provoking an idea is, made up of cuts and pastes of fiction and non-fiction, don't take it in unless you can find evidence to back up the statements.
One final note. Going back to basics, there are fundamental differences between Buddhism and Christianity:
... one significant element being that while Christianity is at its core monotheistic and relies on a God as a Creator, Buddhism is generally non-theistic and rejects the notion of a Creator God which provides divine values for the world. [...] There are other fundamental incompatibilities, e.g. while Grace in Christianity is part of the very fabric of theology, in Theravada Buddhism no deity can interfere with Karma and hence the notion of any type of grace is inadmissible within these teachings.