I started to watch the video and it was almost ridiculous to see that the game can be completed in 3 minutes. Then I noticed that I had almost got to the next checkpoint with my best attempt. I just didn't manage to grab the last platform before the checkpoint (1:39 in the video). Now I wondering if I should stop watching and try to still finish the game on my own.
I'm very familiar with the problem of creating games too difficult. It has happened to me in many, many projects and for some reason that is a mistake that I find super difficult to learn. Even when I think that this time I will make it easier, it still ends up being relatively difficult! So I'm starting to think that the game should be almost boring simple for the developer to have the right amount of difficulty to others. When testing ones own game it must be remembered that one always have had a lot more practice that the players will have when starting to play the game. One is also likely to be more motivated to play their own creation compared to average player so they also do not get frustrated as quickly as the player. The best case scenario would be to have a playtester that does not know how to play the game previously, let them try it out and then edit the game afterwards accordingly. Especially if the player dies many times at same point (I pointed some examples on my first message) there is a high risk of getting frustrated and those would be the most important points to fix. I don't mind dying and restarting if I feel I'm making progress with (almost) every attempt but dying on the same spot too many times can get me to quit.