I know what you mean by "I do find that the readings in HWMonitor can be a bit sporadic''.
However I've found for my system HWMonitor to work great, and show actual temps. I've never experienced such high jumps as shown in your video though, but there again every system is different.
For a long time I was messing around with allot of different temp software, and found HWMonitor to be the most reliable for me.
Great setup though mate, let me know if you post any other new vids!