I have not tried it via the network, only on my local Kubo node. That worked decently well but is probably just a kind of overhead when reading it from local storage.

Chunked files should work well for video streaming of static video files, yes. Given that you have a reliable node to fetch from, it would probably be fast enough and support seeking (skipping to a certain timestamp).

Your real benefit is probably going to be the caching, immutability, and potential pinning as well as redistribution.

For most live streams, it would probably not be a good fit. But maybe with good signaling for a client to receive IPFS addresses and a very reliable and fast node to fetch from, it might be an option to stream a video in small chunks. But maybe your use cases favours completeness and immutability over stream stability and low latency.