"Sora is included as part of your Plus account at no additional cost. You can generate up to 50 videos at 480p resolution or fewer videos at 720p each month."
@sfoster is the 720p a new addition or you didn't include it in your post?
If you want to try a free one try https://www.bandlab.com/mastering
But one I liked better was https://www.waves.com/online-mastering (still free to try)
Oh hell no I would not trust it to mix anything. The mastering AIs though are really algorithms like you say and just enhancing things, like an "Auto Fix" button in a photo editor instead of doing it yourself. I mean if I can take my crappy rehearsal recording and before I send it to my band...
What about a short clip at your highest graphic capacity? I mean the above is an hour and if the graphics are inferior because you wanted a long test, it's a lot to watch lol. But I did skip though but was concentrated on graphics of course.
If you have to lower the graphic quality to test faster I'm just wondering why the test is shared and why that is not explained. I think most of us are looking at the graphics and not wondering how fast python was.
Not sure what you were working on but I thought your top effect was with the water... ripples, etc. and the least effective was the clouds/fog. Hope this helps.