He makes two completely faulty assumptions:
1) Only Chinese people buy from Alibaba.
I co-own a retail store here in the US and we order a lot of stuff from Aliexpress. We are a Gold VIP on Aliexpress ($4,000 in sales every 90 days to maintain this level; we do about $1.5-2K/month average on there.)
If you read the reviews of products on Aliexpress, you'll see reviews in just about every language--English, French, Russian, etc. In fact, very few of the reviews are from Chinese customers. Ali is most definitely a platform (two different platforms, actually, with Aliexpress and Alibaba) for China to sell to the rest of the world. Not necessarily for China to sell to China.
2) They'd need some sort of huge fulfillment centers a la Amazon.
The genius of the Aliexpress business model is that it works like eBay (Alibaba I'd more likely compare to LinkedIn, as it's even less centralized.) Sellers fulfill orders themselves, post tracking numbers, and live chat/message with buyers to complete the loop. Some sellers take Alipay, which is the Paypal to Aliexpress's eBay. Others take Paypal, wire transfers, etc. There is absolutely no gigantic warehouse needed by Alibaba.
All of these assumptions that he guessed so wrong on could have easily been disproven by ordering a few $2 items off Aliexpress and having them shipped to his house to see how the business model works. It's pretty straightforward!