It is a very cute clip. But don't be fooled. Their ability to sing Hebrew songs doesn't make them Jewish. I can sing Awimbawe, that doesn't make me a long lost African. And anyway, a few features of their song just don't add up.
If indeed they were a lost tribe of Israel, clutching on to their traditions for thousands of years in spite of their dislocation from other Jews, why do they chant the Shema in a distinctively modern European tune? Why do they sing it in English after singing it in Hebrew? And what is the explanation for the placards they display with English quotes from the Bible?
The explanation is a simple. These tribesmen are not performing an ancient rite, but rather singing the Hebrew songs that Christian missionaries have taught them. For hundreds of years the missionary work in places such as Africa and Papua New Guinea has introduced biblical ideas to native populations.
So we shouldn't be so surprised to find a witch doctor in Burma wearing a tallis or a hut in the Sahara Desert with menorahs painted all over it. It is probably just the result of our Christian friends teaching our bible (and theirs) to the locals.
Jews do not missionise. We don't believe in converting the world to our ways. But we certainly believe that ethical monotheism, the belief in one G-d Who expects us to live morally, can improve the lives of all peoples around the world. If that is what the missionaries teach, we say Amen.