Here are some videos that folks have recommended either on reddit or one of the many #hamradio mailing lists that I subscribe to.
DX Commander on delta loop antennas
Delta loops are great antennas. Here’s a tutorial on how to build one.
AD0WE on Morse Code speed vs. proficiency
Kurt, AD0WE, has done a great deal of thinking about how we learn and get better at CW—way more than I have. He has a lot more info on his Morse Code Ninja website.
M0NTV on matching diodes
M0NTV likes homebrewing diode mixers, and because one of the keys to success is using matched diodes, he’s developed a methodology for doing this.