"The thing in the corner looks off" is the kind of feedback that earns you a revision round of clarification. The fix is to show the editor exactly what you mean: a screenshot of the exact frame, a red box around the problem, pasted as a timestamped comment. Here's the technique.

Pause your video in the MarketScale proofing room at the exact frame where the problem appears and take a screenshot. On a Mac, that's Command-Shift-4 to grab a selection. You now have the precise visual the editor needs to see, captured from your own video. Screenshot your MarketScale video, not a different version floating around elsewhere, so the editor is looking at the same source they're working from.

Open the screenshot in Preview (or any markup tool) and draw a red box around the exact element that needs changing. The lower third, the logo placement, the spot where the cut feels wrong. The red box removes all ambiguity about which part of the frame you mean. The editor doesn't have to guess whether you're talking about the text or the background; the box points right at it.

Paste the marked-up screenshot directly into a timestamped comment in the proofing room, at the moment on the timeline where the issue occurs. Now the editor has all three pieces: when (the timestamp), where in the frame (the red box), and what it currently looks like (the screenshot). That combination is the most precise edit instruction you can give, and it collapses what would have been a back-and-forth into a single clear note.

On your next revision, instead of describing a visual problem in words, screenshot the exact frame of your MarketScale video, draw a red box around the issue, and paste it as a timestamped comment in the proofing room. The editor fixes exactly the right thing on the first try, and you save a revision round.