OK. Found it:

Displayed using Sixels or the Kitty protocol. Supported input formats are PNG, JPEG, BMP, GIF (stb_image), WebP (jebp) and SVG (nanosvg). Opt-in; edit the config to enable it.

Inline using sixel. Go look at the screenshots, it's not bad.

Yes, screenshots are nice. That's why I asked.

btw.

Rendering images or movies on the TTY is common.

fbida: https://www.kraxel.org/blog/linux/fbida/

mpv: https://mpv.io/

Fbida sometimes need the -d option pointing to /dev/drm/something, when using screen or tmux.

MPV required for years -vo=drm on the TTY but since some months it always works. Nice improvement :)

A display server is not needed.

It is first time I saw it today. Thanks!