I've been using Cloudflare's ecosystem heavily for my video tools and can share some thoughts:

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.

I’ve used Netcup to run an ffmpeg transcoding fleet, stored in Wasabi, served via BunnyCDN. It worked great, and I had total control of everything. You might also check out Bunny’s video services which didn’t exist when I built out my solution.