Forgive me I could only bare to watch half the video I am afraid it is nonsense.
The Palestinian people are those people who lived in the area before the end of World War I, they consisted of Muslims, Christians, and Jews who have been intermarrying millennium in the same area, genetically mixed with various other peoples including Egyptians, Hittites, Assyrians, Romans, Greeks, European Crusaders and many others.
In the early modern period and especially in the 19th Century European Jews have in small numbers migrated to that area. During the rise of anti-Semitism more people came there during the 20th Century.
All this argument about original inhabitants is just garbage. What is being argued genetic derivation? Religious affiliation or cultural continuity? None of which can establish any particular group as original --- it is ridiculous.
People today are living in refugee camps, confined within the Gaza ghetto and West-bank encampments, their lands taken from them --- they are the Palestinian people, because that is the 'protected' state they came from albeit only invented by Western powers at the end of WWI.
The reality does not evaporate because of such abstract and meaningless. The video is a concoction of historical snippets. Assad's comments are about Ottoman Syria (Eyalet of Damascus), because Baathism does not accept the right of divisions of Western Powers in 1918.
Perhaps it would be better to outline the principles of nationhood that makes 'original ownership' pre-eminent over the lives and property of living people?
Sorry I should not be so harsh, but I am afraid such 'documentaries' are more like desperate propaganda than reasoned argument.