Roughly 330 lbs. of coal are contained in the combined hopper and fire tube. I'd guess about 260 to perhaps 270 lbs. in the hopper proper. Most I've ever burned in one day is 105 lbs. when it hit -17 degrees here. It could come right close to surviving 3 such full days in succession without a feeding.
The ash tub is huge. I generally swap my ash tubs out for every 260 to 280 lbs. of coal consumed, but the tub is only at most 2/3 full at that juncture. To get the ash tub closer to full would probably (and I'm guessing here) require the burning of about 400 to 420 lbs. of coal. Thats 4 days with -17 degrees for the low in my case.
The only adjustment it has is to set the ashing (stokes by ashing) temperature on (what I refer to as the) ash sled. Calling it a grate would in my opinion be a great injustice. It could perhaps crush ash grates and spit them out into the ash tub. It certainly laughs at and spits out clinkers, regardless of size.
A video wouldn't show you very much. There isn't a fire chamber door that you can open to see flames in the fire pot as for conventional boilers. In fact, it doesn't have a fire pot, as it burns coal in more of a "fire tube". With coal in the gravity hopper above, at best you might see the coals get red and witness the blue lady flames at the lower level of the "flapper" (port cover), but often mine only has black coal sitting at that level (which is often just above the fire level). Best opportunity to see the blue ladies and the orange glow is immediately after a firing session.
Boring but reliable and hands off heat (year round for my case). Gotta love it.
The biggest oddity perhaps is that if you are planning to shut it down in the summer months it takes 22 days for the completely full hopper and the fire tube to run out of coal, as it only burns about 13.5 lbs. per day (in my case) to provide our home with DHW. So my shutdown planning requires that I stop feeding it 22 days before fire out, and 23 days before cleaning day.