I gave it two and a half minutes.
The Latin variant of the name Croat was mentioned for the first time in a manuscript in the 9th century. It comes from the Proto-Slavic xrvat, xrvatin and has cognate forms in numerous Slavic languages.
In Croatia, the name Croat was used before the 10th century to refer to the area of the Zadar, Trogir and Split hinterland. This refutes the argument that the ethnic name Croat was not mentioned in Dalmatia.
If you want a reference source, see the Etymological Dictionary of the Croatian Language by Ranko Matasović, 2016, page 338. If you choose to continue this discussion, please don't use YouTube videos to back up your arguments.
Good luck.