Do we know that they spend money on this or is that inferred?
I asked because the search you've linked to only seems to list relatively niche chess videos on one creator's account. And the videos themselves are also ad-supported. It's (at least) not impossible that the sponsorship association is not budgeted in the way that (I think) you infer.
"I watched Daniel King for 10 years and have previously donated to him, now I am happy that we are in position to sponsor his work which I believe is extraordinary.", this also definitely sounds like monetary compensation to me.
I asked because the search you've linked to only seems to list relatively niche chess videos on one creator's account. And the videos themselves are also ad-supported. It's (at least) not impossible that the sponsorship association is not budgeted in the way that (I think) you infer.