For the first one, its just this type of file right here used as hit-lighting/hit-lighting@2x.png. Osu automatically just makes that ripple so it looks cooler. If you want to test it, I made a file here:
LinkHit-lighting@2x.png <- FIle name of this image ^ ( The image is there, I just made the circle white )
LinkHit-lighting.png <- File name of this image.
Put it in your skin and make sure you have "Hit lighting" ticked in your settings until detailed settings.
For the second one, look at this picture:
( forgot to include but 300.png is also made transparent
These following are made transparent ( basically they're just an image filed named these with a blank pixel so the 300s and the little sparkle effect you see in the osu default skin don't show when you successfully hit ) with just hit lighting ticked. If you add a hit lighting image, then you can get the ripple effect like so in your first video. If you don't add any image, thats the default hitlighting you see, which is a glow.
Tell me if you need help with anything else and hope this was helpful!
