First of all, you can improve your time by 10min by editing your video title. It should be 28min if I added memo and exec time correctly
Second, 2min memo per cube and 1min exec per cube looks pretty normal. So I wouldn't say that you have a memo problem. Further progress will probably come from simple practice at this point.
But since you asked for memo advice, I will give you my opinion. I'm currently at a similar level of 15+ cubes per hour. So you might find something helpful. I'm assuming that you have a good list of letter pairs and that you have practiced with your letter pairs and your rooms quite a lot. If not, this is something to address.
I also memo in packs of 4 and subpacks of 2, but like this: memo 1-2, review 1-2, recall 1-2 (basically test if you can recall everything). Then memo 3-4, review 3-4, recall 3-4.
A 13-cube attempt would then look like this (memorizing 4-packs as described above). Memo 1-4, memo 5-8, do an extra recall of 1-8, memo 9-12, memo 3BLD cube, solve 3BLD cube, solve 9-12, solve 1-8. You can see that I solve the last 4-pack first. This way, you can usually avoid an extra recall/review of this pack which might save some time. This inverse order is also used by many advanced MBLDers.
Besides this inverse memo/exec order I would recommend practicing 4-cube attempts a lot. Try to rush through your memo a bit more with every attempt until you cannot recall it anymore. This way you get a lot of good practice and can push your memo speed more and more. You should also analyze every mistake that you make by using the same scrambles and trying to figure out what went wrong.
I hope some of this helps. Good luck!