SCRUM MASTER FRAMEWORK (PSM I)
YOUTUBE

In this video course from 2022, created by Agile for Humans, you can learn Scrum and prepare for your PSM I Certification with Professional Scrum Trainers Ryan Ripley and Todd Miller.
There are 20 short videos (about 5 minutes each) in this YouTube playlist.

CERTIFIED SCRUM MASTER (CSM)
YOUTUBE

This full course was created by Simplilearn and can help you prepare for the Certified Scrum Master exam (CSM) from Scrum Alliance.
It's a 3 and a half hours video that covers the Scrum Guide, principles, and expands on the Scrum framework and how it can be implemented in projects.

SCRUM FUNDAMENTALS CERTIFIED (SFC)
YOUTUBE

These videos are created by ScrumStudy and supplement their preparation for the SFC exam. You can also view those as part of a Udemy course from ScrumStudy.
About 1 hour of videos.

SCRUM FUNDAMENTALS (CSM)
Learnupon

The video course is divided into 4 sections, which you may complete in any order you wish. (Alternatively, you can choose to skip directly to the course quiz to assess your current skills before exploring the content.)  
There are 8 modules in the course. It is free, but registration is required.

Agile with Atlassian Jira
Coursera

This course discusses common foundational principles and practices used by agile methodologies, providing you with a flexible set of tools to use in your role (e.g. product owner, scrum master, project manager, team member) on an agile team. 
It is free, but registration is required with Coursera.
ScrumIdeas provides freely available information and resources for understanding and using the Scrum framework. Here you can find a range of materials, including articles, videos, and courses, that cover various aspects of Scrum and Agile.