Just because a file is encoded as H.264 does not mean it is streamable. The encoding needs to be done in a way that makes streaming realistic.
For the rest of it, I would suggest an ffmpeg solution on a server. You can have it re-encode just the requested times while encoding to a streaming friendly format. There are JS libraries available that allow you to use HLS in the native <video> tag.
For the rest of it, I would suggest an ffmpeg solution on a server. You can have it re-encode just the requested times while encoding to a streaming friendly format. There are JS libraries available that allow you to use HLS in the native <video> tag.