Hi Chris,
You have a few issues there, I think it's always best to work on one at a time, also people will respond to one issue at a time rather than a list!
So with this said for the embedded video having different colours this is known and is due to the fact that only Firefox seems able to read the colour profile of both the image and the video. Other browsers can only read the colour profile of the image, so the video will have a different colour because it can not read it.
So the fix is to use an image mask, here is an example:
https://support.ggno.me/forum_projects/bbq
You will see a button to toggle the image mask.
How this was built?
If you follow the video on how to embed video,
https://ggnome.com/doc/embed-video/
At time index 8:52 you will see I add a mask to the video.
Once you have finished making the video, drag the mask from the video layer to the patch image layer and invert the mask, on the Mac its Command + i, you will end up with a patch image with a hole, the video will display through the hole.
Export the patch image as a PNG, then add this to the project using the same placement values as the pinned video.
Using the list view you should have the pinned video above the pinned image.
The lower an element is the more forward it will be.
As this is an image, the browser can apply the correct colour profile eliminating the hard edges so you should only see a colour difference around the hole in the image mask.
In the BBQ example, it is easy to hide.
To help understand I have attached the video I made then the patch image PNG with the inverted mask.
Regards,