I created lorem.video - a service that generates placeholder videos directly from the URL. For example: https://lorem.video/1280x720_h264_20s_30fps
You control everything via the URL path: resolution, duration, codec (h264/h265/av1/vp9), bitrate, and fps. Videos are cached after first generation, so subsequent requests are instant.
Built it in Go using FFmpeg for encoding. Generation runs in a nice'd process so it doesn't interfere with serving cached videos. Running on a cheap VPS.
MIT licensed, source on GitHub: https://github.com/guntisdev/lorem-video