Possibly because you wouldn't have a lorry in your kitchen! (A matter of scale? )[...] I would dump my lorry full of wheat at the depot, I would pour my wheat in the kitchen (if I actually ground wheat in the kitchen). [...]
Unless you're thinking of taking a lethal overdose by dispensing the whole contents of a large container of pills, I wouldn't say "pour": there usually wouldn't be enough pills to get that continuous flowing action.I saw a video earlier and the guy was putting effervescent pills out of its sachet he said "... and we're going to start dumping the pills", that was the moment when this doubt came up, do I pour or dump pills? [...]
I agree.If you had a shopping bag full of small things (sweets, for instance), you could dump them out on the table, implying a quick action that empties the bag in one go — or you could pour them out steadily. (In that context, I wouldn't use "put", "drop" or "throw".)
Similarly, if that bag were full of marbles or sugar cubes, the same usage could apply. I agree that we wouldn't say "pour" for just half a dozen marbles or sugar cubes.
OK, that's a very unusual context, and not at all typical of general usage. I suppose "dump" would work if he's going to throw them away after smashing them. That's a rather different sense of "dump".I think there were 20 sachets. It's a prank video, he smashes them until they're like powder. I guess "dump" would fit better