I watched a documentary which basically claims that modern-day Romanians are not the descendants of Rome, but that the Romans and the Romanians share a common ancestor with the same language. One of their stronger arguments is that it's impossible for the Romanian language to become so latinized in the 150 years or so in which Rome occupied a small part of Romania (I think they said about 16%), because in other places where they occupied a much greater region (such as Egypt) the languages only show traces of Latin. What do you think, is this a good theory? There is also a part 2 in which they also show genetic evidence among other things, but I was not able to find a translated version of it. If you would like more detailed information from part 2, please let me know. Thanks.
I'm not a linguist so I can't comment on whether 150 years are enough or not to thoroughly Latinize a language. However, I think I can point out that the analogy with Egypt is deeply flawed.
When the Romans conquered Egypt from the Ptolemaic dynasty they took over a country that had roughly speaking two distinct populations: a "Greek" elite and semi-elite that was already Hellenized and spoke Greek and a native Egyptian population which spoke its own language and took no part in the political, cultural, administrative or financial affairs of their masters (except for the priests, but they were a thin layer which was probably as distant from the plain native folks as the foreign overlords).
With the advent or Roman rule nothing much changed for the Egyptian native peasant - he kept tilling his land, paying his taxes and had as little need or incentive to learn the language of his masters as before. Therefore, small wonder that his own language bears few traces of theirs.
Why was the linguistic situation different in other modern-day-Romance countries which the Romans conquered (such as France or Spain)? I think it's because in these countries the mass of native population had willy-nilly constant contact with the Romans and adopted eventually their language. A new elite grew up through trade and services to the Romans which associated itself with Latin. On the other hand, in Egypt there were no conditions for the rise of such an elite because there was little internal trade and the Romans did not settle the hinterland densely or required the direct services of the natives, having the "Greek" segment of the population at their beck and call.
So, to sum up, the comparison of Romania to Egypt is not a valid one.
P.S. There was a third major part of the Egyptian population at the time: the Jews. But for the purposes of this discussion this is not crucial so I left this fact out to keep matters simple.