Hi lagin,
I agree with the others that you should increase the tempo just a bit. Don't forget though that on page 6 you'll need to contend with the more complex RH chord figurations, so will need some reserve strength and stamina for that. This is an athletic piece.
A few thoughts:
From your playing, I think you've discovered that this piece is all about contrasts--distinguishing nonlegato from staccato, foreground from background, wrist octaves from forearm octaves, etc. You're doing a good job with those contrasts.
In not using pedal in measures 15-16 you're doing exactly the right thing.
In measures 18-20 in the fourth beats, you use the 5th finger for the top notes there. If you instead use 4, 5, 4, 5, it will be more legato and less tiring and tension prone. Those groups are under slur marks.
In Part B, I would relax the tempo there to luxuriate in the lyricism. Rachmaninoff has marked it "un poco meno mosso", or less animated. You're doing well striving in the LH for a "quiet lake effect" acompaniment, i.e., no ripples on the surface of the lake. Easing the tempo a little will further facilitate that effort too.
In 41 you're scrambling for the notes on the leap to the downbeat there. Here's a solution: Finger the LH in the fourth beat of the preceding measure (40) with 5, 2, 1, 4, 1. Then allow the RH to take the last note of that group with 2. The RH has already finished the G octave up in the treble staff and is available to assist. Playing the A with 2 as mentioned positions the RH to take the F# chord on the downbeat of 41 easily. More importantly, it then gives the LH very precious time to start the leap earlier to the low D, thereby better assuring accuracy. This is one of those spots where redistributing the music between the hands has solid justification.
I agree with the comment made earlier about bringing out the inner lines of Part B--but never at the expense of the primary melody, of course. For example, in 46 in the third and fourth beats, there is in the RH that inner scalar line of D, E flat, and F leading to the G in the RH on the next downbeat. A way to give it ultimate clarity is to reduce the texture there (yes, eliminate some notes as an option). Thus, you would play the D, then the E flat and lower C as double notes, next the F and harmonic B flat and finally the G with the lower E flat. Then when you play the following D octave, the effect is soaring and awesome! Or, if you insist, at least play it as I've suggested to fix the sound in your ears, then add back the full texture, but striving to etch that line.
Your video cut off prematurely, but you played the poco a poco accelerando well. Just be sure on page 5 that you resume speed by the Tempo I marking, no later. There can be a temptation to make the accelerando too gradual and drag it out too long.
In your grading scheme, I would say you've got this prelude at a Level 7 at the moment. Perhaps once you've got the piece further along, you could re-post it--but the whole thing, please. Keep up the good work!