Repeat after me: The pyramids were NOT built by aliens. According to ancient Egyptian texts, the pyramids were built by humans WITH THE ASSISTANCE of the "Guardians of the Sky," or the "Teachers from Heaven," the "gods," who descended from the sky in "flying barges"... (If you're wondering what "texts" I'm referring to, check out the AL-KHITAT by Al-Maqrizi.) (source)
Now, this almost counts as a real citation of "ancient Egyptian texts," except for one thing. Al-Maqrizi (1364-1442 CE) was a medieval-era Muslim historian, and his Al-Khitat (more properly, the Mawaiz wa al-'i'tibar bi dhikr al-khitat wa al-'athar) was written around 1400 CE, almost FOUR THOUSAND YEARS after the pyramids were built. Clearly, for Tsoukalos "ancient texts" is a rather elastic term.
Al-Maqrizi did in fact draw on many genuine ancient texts of greater or lesser reliability, though these were classical Arabic texts of the first millennium CE, not ancient Egyptian records, written as they were in a then-unreadable tongue. Despite this, his history carried a great deal of authority in the fifteenth century, but nevertheless, in order to use Al-Maqrizi as an "ancient text" in support of the theory that aliens assisted with the building of the pyramids, Tsoukalos would need to demonstrate a series of things, not least of which is whether the passage from Al-Maqrizi derives from a genuine ancient text and whether the original text is reputable and accurate.
Significant doubt exists on this matter because Al-Maqrizi was not particularly well-informed about ancient Egypt. He believed, for example, that hieroglyphics were a secret code for alchemy, something that the modern decipherment of hieroglyphics disproved. He also made claims for marvelous materials being stored in thirty chambers beneath the Great Pyramid, which no excavation or exploration has found. (Logically, if the story of the chambers were true, they must have been accessible; and since they are not, then the story can't be true unless one believes folklore lives four thousand years unchanged.)
So, let us give Tsoukalos credit for attempting to cite an "ancient text," and then let us criticize him for not quite understanding what an "ancient text" is or how one should judge the accuracy and reliability of its contents. After all, in 1400, the "ancient texts" of the era claimed that the pyramids were in fact Joseph's granaries.
In the near-contemporary Travels of Sir John Mandeville (c. 1357-1371 CE), for example, the three pyramids of Giza (two large and the third smaller one) are described this way:
And now also I shall speak of another thing that is beyond Babylon, above the flood of the Nile, toward the desert between Africa and Egypt; that is to say, of the garners [= granaries] of Joseph, that he let make for to keep the grains for the peril of the dear years. And they be made of stone, full well made of masons' craft; of the which two be marvellously great and high, and the tother ne be not so great. And every garner hath a gate for to enter within, a little high from the earth; for the land is wasted and fallen since the garners were made. And within they be all full of serpents. And above the garners without be many scriptures of diverse languages. And some men say, that they be sepultures [= tombs] of great lords, that were sometime, but that is not true, for all the common rumour and speech is of all the people there, both far and near, that they be the garners of Joseph; and so find they in their scriptures, and in their chronicles. On the other part, if they were sepultures, they should not be void within, ne they should have no gates for to enter within; for ye may well know, that tombs and sepultures be not made of such greatness, nor of such highness; wherefore it is not to believe, that they be tombs or sepultures. (Chapter VII)
So, given that medieval knowledge of the pyramids was spotty at best (unless one truly thinks them giant silos), we need something more to judge whether a particular story, especially a fanciful one, from a medieval manuscript ought to be believed. This is never more true than when claiming that the medieval texts should be used to overturn everything we know about the history of the era four thousand years before they were written.