It's hard to say without having seen the YouTube video in question, but cultists worshipping the Great Old Ones, of which Cthulhu is the best known, are often described online as promising that their followers will be devoured first (or sometimes last). It seems to be a "meme" of sorts. Examples:
Cthulhu For President promises this:
Cthulhu cultists will be given the following privileges: They will die last.
Who Will Be Eaten First?, a Chick tract parody
A made-up Cult of Cthulhu card for a made-up "metaphysical card game":
Easily offended? Not at all! Those who we don’t like will be kept safe and cozy to witness the full awfulness of the Coming of the Eldritch-Gibbous Elder Gods! Then the cultists will be eaten first, and the others left to slowly perish under the pseudo-pod feet of the implacable Tsathoggua, Shub-Niggurath et al.
The parody "Wikipedia" Uncyclopedia's article on Cthulhu:
The cathedral of the Universal Church of Cthulu, located just outside Providence, Rhode Island (hellmouth-adjacent), offers pot-luck dinners every Saturday, for those who wish to be devoured first.
The band A Walk With the Wicked's song "Ancient Servant" from the album Bleated Apocalypse includes lines like "The dread god lies entombed / Not dead but dreaming" (a clear reference to Call of Cthulhu) and concludes like this:
Offering human sacrifice
To gain your favour
Be spared the terrors
And be devoured first
The online blog article "Repent, Atheists! Or be devoured by Cthulhu!" has a comment which says
[...] Actually, believers get devoured first.
Random reddit user's image caption
These are all just people saying things online without any canon repute, but since you're actually asking what deity a YouTube video referred to, I'm inclined to assume it was Cthulhu based on the widespread notion that his worshippers will be devoured first (or last; at least his cultists promise that cultists will be given preferential treatment, depending on when you prefer to be consumed).
However, I can't find any similar sentiment expressed in any of Lovecraft's original stories, so I'm not sure this belief is canon among the cultists he wrote about. This forum post does assume that this is true "based off HP Lovecraft's work", though, so I might just be bad at searching.
I'm sure this meme originated somewhere, though, so perhaps someone well versed in the Mythos can write a better answer – had your question been "Where did the belief that Cthulhu cultists will be devoured first when he awakens originate?", I'd not have answered, but I still think the deity you're thinking of is Cthulhu.