It's better if you learn some terminology used in osu! cause people gonna get confused. (Had to google minims, first time I hear of that name) Quarter note - 1/1 (1 beat), 8th note - 1/2 , 16th note will be 1/4.
According to wikipedia definition "minims" are half notes, which in osu! system will be 2 beats long note, and notes you struggled with weren't those.
You can do them by learning to single tap fast or alternate (which requires good speed control). Surprisingly, you have to practice to do it both ways.
agreed with sarasseo, i suggest you focus on accuracy/rhythm more than playing fast songs (at first) because it looks like you're mashing throughout the whole song and hoping for the best datsigdoesotrue._.
play slightly easier songs, ones that you can achieve at least 95% accuracy on so you can get used to tapping consistently
also in your video from 2:33 to 2:36, you should try to maintain that rhythm with the single circles
play a lot more as well, worry about speed once you get better
if you want to get better, never mash the notes. force yourself to single tap everything other than 1/4 tick notes (aka sixteenth notes). Mashing your way through a song doesn't help you get better at single tapping. Developing bad habits is how to decrease your improvement.
Only do it if you are desperate in trying to beat a song, but if you are just looking to get better only click z or x the minimum amount required to pass the pattern.
as long as we have circles to click, no anger shall harm us
I'd also suggest learning to single-tap, and only alternate on 1/4's.
Learning alternating is like being a fish, swimming in your own personal pond. You can ask for help and practice maps, mostly oriented for single-tapping, from single-tappers (nearly everyone single-taps), but alternating info is few and far between because there are so few good alternating players. Learning for yourself is important regardless, but I suggest you just go mainstream and learn to single-tap first... if you can't figure things out for yourself.
Otherwise, I suggest you go find some good alternating players, try to learn from them and just practice, because you're only gonna get told to single-tap on these forums when you ask for help with alternating.
I used to full alternate but later on when I turned to single tapping I sucked at alternating and I had a bad habit of spamming whenever I had to alternate anything at all, single tap for a week or 2 (depending on if you actually play a bunch) if your still not comfortable with it stick with alternating
I see that you are alternating, I alternate also, this choice could be one of the worst choices to choose if you force it. You shouldn't force alternating because in my opinion there are a lot of top ranks(and by a lot top ranks I mean almost all top ranks) that only alternate 1/4 so you can completely get good at single tapping. If however you feel EXTREMELY comfortable with alternating and EXTREMELY uncomfortable with single tapping I suppose you can stick with alternating. Though your problems could not only or not at all be alternating, it just could be you having trouble reading this section, play slower songs to get a feel for it more is all I'm going to say if you are going to stick with alternating