These videos were probably created in preparation for job interviews.

https://invidio.us/channel/UCzDJwLWoYCUQowF_nG3m5OQ

The video creator seems to be a Senior Consultant for Amazon nowadays. The most recent is two years ago and they improve in quality over time. The algorithms are basics, though one may be rusty or have gaps in education. *cough* At least I found one of them useful...