When you're booking a Replay Review, attaching a video is a key part of the process. And sometimes a student will inadvertently submit either the wrong video, or one that they aren’t finished marking up with match indicators and such.
At this time there isn't an edit button you can use after submitting your gameplay video. What you’ll need to do is contact your expert, either via Metafy chat or on Discord, and ask them to cancel your review.
Cancellation will return it to you in a rejected state, and once that’s done you can move it to Drafts and modify it as needed. There’s no cost involved as you’ve already paid for your Replay Review. Once it’s ready you can resubmit it.