Okay, I am going to "piggyback" on a previous Superior Threads video post because since I saw that post I have viewed several of their videos and am hooked! Bob Purcell, "Chief Threadologist of Superior Threads", holds a wealth of interesting and in my opinion invaluable information in that brain of his and he is sharing it on these videos. They are posted in short little clips addressing specific topics regarding thread, your machine, and sewing. Each containing little tidbits of information which I would have probably not obtained elsewhere and they are from a reputable source.
These videos are definitely worth checking out. Superior Threads has their own channel here on YouTube where you can pick/choose/view your choice of videos.