This happens all the time with all kinds of video searches, both specific and general, and is highly dependent on the query wording; here is an example:
If I search "cracking the cryptic" -- a prolific and popular youtube channel, I get no results:
but if I misspell "the" and search "cracking hte cryptic", the correct spelling shows up in many results:
if I omitting "the" entirely, I get just four results, all about cryptocurrency, and none of the expected videos: 
(The misspelling makes me thing it might have something to do with caching?)
In my example, "cracking the cryptic", "cracking hte cryptic", and "cracking cryptic" should all return basically the same results -- a collection of the results I'd get searching that phrase on youtube, tiktok, dailymotion, etc.
Searches that return plenty of results searched natively on youtube, tiktok, etc should definitely not return zero items on Kagi's SERP; and I should not need to cleverly misspell my queries to see valid results.
