IPFS file's HTTP header should include "content-length"

I tried IPFS Gateway.

Cloudflare’s IPFS Gateway and IPFS official gateway is something difference.
I noticed difference is HTTP header’s content-length property.

It become a problem with video files.
If don’t response content-length, web browser can’t stream (range HTTP header streaming) video and one of browser is can’t play.

For example, check this links.