Ordered series rather than one-off videos. Start at the beginning and the next one assumes what the last one covered.
Networking Fundamentals
Eight lessons covering the ground everything else stands on: what a network actually is, addressing, how a switch decides where to send a frame, how a router decides where to send a packet, and why subnetting is not as bad as it looks.
If you are starting CCNA study, start here. If you have been running a home network for years and have never been quite sure what a default gateway is doing, also start here.
Series in progress
OpenVPN on EdgeRouter — five parts, from certificates through to a working tunnel and the routing that makes it useful.
Written versions of these courses are being added here, so you can skim, search, and copy a command without scrubbing a video timeline.