Please help!

I shot a short video of a colleague talking to camera outdoors.

Everything is static (ie still) apart from slight movements of my colleague as she talks.

There was some dirt on the lens which caused a small mark on the blue sky, just to the side of my colleagues head.

I have isolated and removed this mark using the Event Pan/Crop tool.

But how do I now REPLACE the MISSING area of removed sky with another bit of sky? (The sky is all uniform blue.)

Please advise me step by step how to do this.

Many thanks!