Hi all! I am just guessing, but my two cents are those guest videos could be categorized.
Something like a very short uppercase description or a hashtag {tutorial, lecture, tear-down, troubleshooting, prototyping, factory, programming, retro, future, review, top, extreme-test, digital, analog, rf, audio, video, general, ...} in every title.
It would be just easier for all to watch one's favorite categories at first when looking at the list of your videos (especially when it looks like people want a truckload of guest videos).
I hope every video will show something more than "Hi! I am a YouTuber and my channel is there. Sub&Like me. [EOV]". Seeing a best-of-whole-channel mashup or a flagship video for every channel would be cool.
Adding categories would also help to keep the rule "don't hate, just select your favorite genre" alive.
It's not like this is a going to a collaborative video, so what value is there on seeing a big Youtubers video on my channel that you already follow anyway?
Collabs (even virtual ones) are cool too.