Video CDN cost is dominated by cache misses, not hits. Cache-miss bytes go cross-continent; cache-hit bytes go to the edge. Even 99% hit rate leaves 1% spending 10-100x more per byte. Multi-tier routing pulls this number down.
Origin shield (mid-tier)
Between edge and origin, add a regional cache layer ('shield'). Each edge node consults its regional shield before origin. ~10x reduction in origin requests. Standard feature in CloudFront, Cloudflare, Akamai.
Per-segment cache keys
URL-segmented HLS/DASH is naturally cache-friendly. Don't put query strings in segment URLs (busts cache). Don't generate new manifests with timestamps (busts cache on manifest itself).
Long-tail tactics
Cold catalog (rarely-watched content): don't shield, just direct-from-origin. Predictive warming for newly released content (push to edges before launch). Tiered storage at origin: hot in SSD, cold in S3 IA.