In Studies in Biblical and Christian Archaeology in Memory of Michele Piccirillo, Jerusalem, 2013, O. Gutfeld and A. Ecker write about the ancient Greek inscription shown in the video above. As regards the dating of the inscription they say (p.168) :
Partial excavation of the cistern has yielded pottery dating from the 5th to 7th or 8th century CE and from the 13th to 15th centuries CE. The flat base of the letters, especially that of the sigma, hints at a date between the 7th and 8th century.This date fits well with the latest evidence of Christian activity at the site (Patrich J. - Tsafrir Y. 1993. “A Byzantine Church Complex at Hor- vat Beit Loya,” in Y. Tsafrir (ed.), Ancient Churches Revealed, Jerusalem, 265).
Unfortunately a dating of late second/early third century is wishful thinking.