Videos within a video overlay

I’m currently working on an extension that requires the ability to show additional webcam footage within the overlay itself. Ideally I want to do this as a peer to peer connection but it seems that overlays block all external video that is trying to be shown. I’ve tried with video tags and with iframe tags (with videos from different sources) and none will work. Is there a workaround for this or is it simply not possible with the standard extension?

Thanks

You are being caught out by the follow rule from https://dev.twitch.tv/docs/extensions

Has any audio (including sounds or music) playing in the extension.

and/or from https://dev.twitch.tv/docs/extensions#appendix-b-guidelines-and-policies

Extensions may not play audio or include code with the intent of playing audio.
Extensions may not use iframes.

Video over video can also be detrimental to the primary function of Twitch, which is, well, playing video

Link to policies is incorrect. Where can I this appendix?