Yep, you're exactly right. The tool works by getting the channel's videos, then fetching the voice-to-text transcripts for them, then searching within the spoken words (along with the title and description) for any keyword matches. So there isn't a feasible way to do that across all of YouTube.

I like your idea of searching the logged-in user's history! That could be handy. Another thing I've thought about is auto-importing all the channels they're subscribed to so they can search within those.

For the first version of VideoMentions Search, I kept things simple with a single "Channel URL" input field, but using their history/subscriptions is totally doable. I'll see if there's enough demand for that.

In any event, I still think that this simple first version has utility. I like being able to quickly pinpoint all the moments when a certain topic was mentioned across all of a channel's videos.

Thanks so much for taking a look, and for your feedback!