Check out this mock system design interview I did.
I've found system design interviews to be a great way to review high-level design and get exposure to concepts I haven't worked with before. In this example, I did some prep by learning about HTTP Live Streaming (HLS), a protocol developed by Apple to enable media streaming that adjusts based on a user's internet connectivity. HLS is used by Apple, YouTube, and Netflix.
Funnily enough, just after we recorded this video, Spotify announced it would adopt HLS for video podcasts.
iOS
System Design
Spotify
HLS
Video