I love listening to Pat Rogers talk about guns and shooting. Here is a free YouTube video of him talking AR-15s.
Pat has quite a few retail videos online with Panteao Productions. The Panteao website has a huge library of videos with many of the big-name instructors in the industry, and they have a subscription based streaming service available which gives you unlimited access to their whole library. I just payed for a month because I have some spare time lately and there was a sale. It's the second time I've ordered a month's subscription.
It was worth it just to watch the Pat Rogers videos again.
They also have AR Armorers videos with Dean Caputo, whom I gather Pat Rogers thought quite highly of. I haven't watched those yet. You may take a look at their library and see if it's worth $20 or so dollars for a month of access if you plan on having a lot of spare time for watching firearms related videos.
https://www.youtube.com/watch?v=0Ej-xCW_YQs