if your extension was on localhost and not a real domain the CSP often won’t apply, coz it’s localhost which has different rules/issues on impementation of a CSP.
This is why “hosted test” exists as it’s the final test to test your extension works as expected on an envinroment that is “like live/released”
The CSP is blocking you using content from this domain, so no.
Given this is “hacky” and undocumented if/when it changes your extension will be broken.
I don’t know of any legal or sensible ways to get around this issue. When using Twitch Clips.
There are also a number of rules and guildelines around sound (staring muted). So in a odd place that you can’t really use clips here. And I would question why you would want clips on top of the video player, (Extensions overlay) since then you have two video/audio sources at the same time which might be taxing on the users system and/or confusing to operate. Especially when if the live stream buffers it could unload or interupt the extension from operating, potentially leaving an audio source uncontrollable.
Any “hacky” solutions where you are (essentially) misusing the API may prevent your extension getting thru review. Since all extensions have to be reviewed by Twitch before they go live for everyone to see them.