Ultra Key not selecting black background
I have imported a simple video I'd like to remove the black background from. Screenshots attached.
I have a white background loaded behind the video which I can see when I crop the clip.
I apply the Ultra Key, eye drop the black background, and set to 100% transparent and for some reason, it just removes patches around the flower, not the full black background.



I've tried:
- Not using multiple screens.
- Manually choosing black as a hex code
- I've played with all of the settings I can find under Ultra Key
- Modify > Reinterpret the footage (oddly this wouldn't allow me to edit any alpha settings)
It's as though the black is already an alpha layer but not transparent for some reason. I purchased the clip from Vimeo so maybe it was compressed and that messed with the file?
Any ideas?
