HA, yea Long GOP MPEG compression sucks with green screen work. Remember the C300 normal doesn't shoot XAVC iFrame or 10 bit for that matter. The MKII has little problems with green screen work, it's fine.
With that said, I haven't tested the URSA's keying potential, I despise chroma key and avoid it like the plague.
I did this for my daughter and my niece. Green screen with the Ursa Mini 4K. The last shot has some keying issues but I wasn't doing it for a customer. ;-) I made everything in it, including the backdrop animations.
Edit: wow it looked a LOT better before MP4 compression and Youtube....so I guess that's no longer a good example.
Edited by Samuel Berger, 18 April 2018 - 10:51 PM.