Hi and welcome to the forum, am not sure who's nest as can't really judge the size ... here is a page of 7 popular ones www.woodlandtrust.org.uk/.../
2013 photos & vids here
eff37 on Flickr
My guess would be Blackbird but far from certain! You would have to upload your vid to Youtube to get the URL to post here!
I agree with tom, it looks like a Christmas wreath, you can still see bits of Leylandi that hads been used to decorate it.
Beauty is in the eye of the beholder.
It's not a Christmas wreath
OK, when I said Christmas wreath, I was thinking of something more like this:
https://www.hobbycraft.co.uk/rattan-grapevine-wreath-20cm/5712641000.html
8 inches across but comes in a variety of sizes.
But the video changes everything. I take it you originally picked up the pot, which had been there for yonks, and found this underneath. The earth has been packed against the rim of the pot and the 'wreath' structure has been worked into the earth implying it was constructed underneath the pot (unless someone put a wreath in a pot and dumped it upside down under the feeder (why?)). Then there are the holes in the ground. Do you have many rats? The holes look too large for mice although both would love the spilled seed under the feeders. Are there droppings? mice are rice grain size, rat are sunflower seed size.