Okay so the main points he makes in that video are:
1) no evidence for Jesus from third party accounts
2) Earliest stuff (ie letters of paul) doesn't talk about Jesus as a flesh and blood person.
3) At the time there was a trend of claiming that Roman gods were actually moral kings in the past, and that Jesus was likely in a similar category.
Now it's hard for me to fully respond since he doesn't give any evidence in that interview, but says he does have it in a book I haven't read, but from what I know of the topic:
1) This is what I'm talking about on misrepresenting how history is studied. There is almost nothing in ancient history that is based on this sort of evidence. Very little back then was written down compared to today, and very little of what was written down has survived. The lack of evidence for Jesus is not remotely unusual or surprising. What historians do is read through these sorts of biased propaganda accounts from long after the fact and try to work out what is most probable.
2) The idea that Paul didn't think Jesus was a real person is rejected by basically everyone else works in the field. Paul clearly says he's met Jesus's brother and that the Roman's killed him, and the religious views Paul expresses make no sense with the idea that he didn't think Jesus was a recent figure. Paul believed the world was about to end and that the resurrection of Jesus proved this.
3) There is no evidence whatsoever that any Christians ever didn't think Jesus was a real person. We know a lot of what early Christians believed, since they wrote lots of stuff attacking each other as heretics, but nowhere is there any mention of Christians who didn't think Jesus really lived.
He also talks about how it's possible that Jesus might be a fictional character who later came to be thought of as real, and this is something that has always annoyed me when talking to mythers. Possible and probable are not the same thing. I agree it is possible for Jesus to have been a mythical person, but little to no reason to regard that as more probable then him having existed.