That was the session opener for the conference, setting the stage. The conference itself (linked from the channel page) has presentations from scientists backing up the claims he makes there.
The first lecture in the session for example is from Dr Clare Craig, an epidemiologist, discussing how the virus actually spreads, and presents evidence for the remark you highlighted about social distancing and quarantine [1].
As I said in other comments here, rejecting arguments based on (lack of) credentials is not constructive. I encourage everyone to open their mind and engage with what people have to say. You can always disagree with them and you're then at least more familiar with the arguments of the other side. I am always trying to find a way to justify the behaviour of governments with regards to COVID-19 - it would sure as heck make my life easier right now to fall in line - and I do this by reading and hearing the arguments in favour of restrictions and mandates from all corners.
[1] https://youtube.com/watch?v=veSfwMZhZRA