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This was well done. It covers machining of the slab-sided (4 part) lower receiver only. It does NOT cover: 1) other partial receivers (billet, forged, or cast) 2) any other aspects of building the AR-15 (such as attaching other components) 3) Metal finishing, such as painting, blueing, parkerizing, etc. of the completed receiver.
What it does cover, it does well. Furthermore, if you are thinking of finishing a partial receiver (any of them), this video will give you the courage to move ahead. It shows how to complete it using simple power tools, as well as with small milling machines. This is especially easy with the slab-sided receiver. This receiver is available from KT Ordinance (KT15B).
Although I'm not building this receiver, the video did eliminate my concerns about finishing a receiver. It's worth the watch, if you are considering such a build.