Netflix differs from YouTube:
Content model: Licensed/produced content, not user uploads. Fewer titles (-) but higher quality and known in advance.
Pre-positioning: Netflix knows what content exists. They pre-encode and distribute to CDNs before release. No real-time transcoding needed.
Open Connect: Netflix's custom CDN. Servers deployed inside ISPs. Content stored in your ISP's data center.
Personalization: Homepage is heavily personalized. Recommendation system is core to the product.