Anonymized historical VOD chat
I would like to use the comments on a VOD to detect moments of interests.
However the only way currently is through an undocumented and unsupported V5 API route that requires making several hundreds if not thousands of requests to compile the entire chat history of one video.
I understand that there are legitimate concerns about user privacy. However I think that the chat could be anonymized, stripped of each username. Even with this left out, making this available on the new Twitch API would be immensely helpful for services such as mine.

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HostileBot commented
So basically the solution is just collect/log everything ourselves? Is access to chat logs being deprecated solely due to privacy concerns then? I can't imagine resource usage would be the issue here.
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At this time, providing a way to programmatically read Twitch Chat on VODs is not a product feature we are considering. However, it is a great suggestion for us to hold onto within UserVoice should there be opportunities in the future to consider this use case.
Although not an exact replacement for your suggestion, we would recommend looking into how live Twitch Chat through IRC can help your service if you haven't done so already.