I recently returned from a trip to Antarctica, and have done a video. A few of the shots have a diffuse circle appearing on them above the center. I believe that it was from a water spot on the lens that I hadn't noticed. You can see examples at 6:48 and 7:22 of the video:
In photos, it would an extremely simple process to remove or conceal the spot. What is the simplest (but reasonably effective) method in Vegas Pro for removing or concealing the spot? For the most part, the shots with the water spot appearing are fairly static.
I had that same sort of problem except with a small insect on the camera. I fixed it by duplicating the track above the original track and masking a small portion of the sky near the spot and on the mask make it so it has a feathered edge. Then I take the entire track and slide it to the left or right to basically duplicate a feathered portion of the sky over the offending area.
Beautiful video you have made.