[af_vet_1981]

They did NOT "forget it"; it is forbidden to use the holiness of Hashem's other names for non-prayer purposes.

This is about the TetraGrammaton, The Name in 4 Hebrew Letters that Moses wrote down. I have read that the correct pronunciation was lost during the Talmudic period after being used as part of the Temple Service during the First Temple period.

With the Temple destroyed and the prohibition on pronouncing The Name outside of the Temple, pronunciation of the Name fell into disuse. Scholars passed down knowledge of the correct pronunciation of [the Tetragrammaton] for many generations, but eventually the correct pronunciation was lost, and we no longer know it with any certainty.

[EinNYC]

This is about the TetraGrammaton, The Name in 4 Hebrew Letters that Moses wrote down. I have read that the correct pronunciation was lost during the Talmudic period after being used as part of the Temple Service during the First Temple period.

We are not referring to the "TetraGrammaton". That is not one of the Names which reflect the different aspects of G-d which are found in prayers. The "TetraGrammaton", as you refer to it, was only uttered by Aaron, the High Priest, in the Holy of Holies, in the Bais HaMikdash, on Yom Kippur. We do not utter any of the Names which refer to G-d in mundane conversation because to do so, for such a purpose, is to cheapen them and is thus prohibited. As I said before, the various Names of G-d each refer to a different attribute of Him, and are only to be used in prayer and Torah study.

So the Messyonic production of that song is not in any way representative of authentic Judaism, in that it immediately violated 2 Jewish laws, just for starters. The Youtube video is even IDENTIFIED as Messyonic:

"Messianic Jewish Alliance of Israel"

and therefore, no further analysis is necessary. It was purposely constructed as a Messyonic attempt at deception. It is a lie through and through, wrapped in a pretty package. Don't try to palm this off as having anything to do with actual Judaism. It's an attempt at a con job. Jews with a proper Jewish education recognize this for what it is at a glance and wouldn't even bother to tune in.