For your use case (40s clips, 10-50K plays/day), Cloudflare Stream's per-minute pricing model could be significantly cheaper than GCP, especially as you scale. Their ABR quality is quite good for 1080p/720p - I haven't noticed quality issues in practice.

One consideration: Cloudflare Stream has a 30s minimum charge per video, so for 40s clips you're paying for 60s. This might eat into the cost savings vs GCP.

Backblaze B2 + Cloudflare has free egress which is huge, but make sure you're using the Bandwidth Alliance properly to avoid surprise charges.

Have you considered keeping source files in B2 and only using Cloudflare Stream for delivery? That hybrid approach might give you more flexibility.

Then you'll need storage(wasabi, backblaze, idrive) and CDN. Bunny CDN or Beluga CDN are, i think, one of the cheapest. Or you can build your own(I did), in case the CDN would pull too much data from origin and cause you increased costs as wasabi gives you only 1:1 egress with stored data and backblaze gives you 3:1. By that I mean that the CDN might always get the file from origin instead of sharing the file among its own nodes. So the origin would experience increased egress.

You can also rent a beefy storage VPS instead. For example, 2x 500 GB NVMe SSDs + 4x 22 TB Enterprise HDDs + 50 TB Bandwidth@2x 1Gbps costs 159€/month.

There are various ways how to do it and in the end it is up to you to pick what works for you the best. Mostly how much work you want to do yourself, how good are your programming skills and how much money you are willing to spend going forward.