I suggest you read the FAQ on this subreddit on this topic, because it has been treated and answered at length. Very few, if any bona fide classicists, historians and other scholars of antiquity regard the Christ myth theory as having any merit. Thinking about it logically, it really makes no sense for the Roman polytheist state church to fabricate a religion that is monotheistic and completely exclusionary of other religions.

The video you posted is an hour and 23 minutes so maybe later I can go about dissecting it but from the first few minutes it does not strike me as particularly good history.