Sitecore is a huge platform with a ton of resources spread across the web. Here are some great video resources for learning (or increasing) your Sitecore knowledge.
Dylan Young’s Sitecore YouTube Channel
Dylan has put together a ton of great Sitecore resources at this YouTube Channel of: https://www.youtube.com/channel/UC5krmrALirwZibfW9-c2JXw
From Development to DevOps, he really covers a range of items.
Sitecore Official YouTube Channel
Sitecore maintains a great YouTube Channel at: https://www.youtube.com/channel/UCr6untnQn62iR3DkcswdKkw
From marketing and C-level content to Habitat and Commerce, this is a great starting place.
Master Sitecore YouTube Channel
Master Sitecore has one of my favorite compilations of technical resources https://www.youtube.com/user/mastersitecore
From Docker to the Virtual Developer Day and Symposium presentations, this is a must “Subscribe” channel. It also has my favorite series on Sitecore Docker (part 1 below)
SUGCON (Sitecore User Group Conference) YouTube Channel
SUGCON is simply awesome. Bringing out devs and DevOps experts sharing their knowledge, there is a wealth of resources to meet your Sitecore hunger. Check it out at: https://www.youtube.com/c/SUGCON/.
Several other Sitecore User Groups and users have their own channels and you can find many of these linked off of Dylan’s YouTube channel: https://www.youtube.com/c/SitecoreMasterChannel/channels
These channels represent a good share, but not all, of the Sitecore video content offered online. Start with these and branch out as appropriate, as you can literally spend days watching these and catching up on conferences past and key technologies driving Sitecore.