Valve Gear Explanatory Videos

Apologies if this is already referenced in a thread elsewhere and I just haven't searched hard enough for it...
I was wondering if anybody could point me in the directions of any videos which do a good, clear job of showing and explaining how steam locomotive valve gear (Walschearts and Stephenson's particularly, but I wouldn't be averse to other types, e.g. Gresley Conjugated, Joy, Bulleid Chain etc) operate. I've always struggled to get my heads around the mechanics of this just from diagrams in a book (my only resource away from an actual loco or model so far), so a video that tells me not only what each bit is, but what causes it to move and what it causes to move would be very welcome and beneficial!

 

http://www.billp.org/Dockstader/ValveGear.html

 

Also worth looking at the late Don Ashton's pages, although they may be more focused on the engineering and/or be more detailed than you need.
Http://www.donashton.co.uk

 

I made a few to while away the first lockdown.

 

Should these be merged with this thread?

Valve Gear Varieties | National Preservation (national-preservation.com)