tl;dr - this guy has a better copyright claim than many of the commentators on this thread may believe
Please note that the below is done without case citations but I can include them if you guys would like them.
I'm going to go against my better judgment here and type out an extended explanation as to why Bold Guy has a better copyright claim than many of you may believe. I saw people say many things on this thread, from the fact that Bold Guy has a terrible lawyer to the idea that Bold guy is filing a ridiculous law suit, that would leave H3H3 in the right. Of course, that's no surprise - this is their subreddit. But I'm going to play devil's advocate here and suggest to you guys why Bold Guy has a decent suit, and why it was taken by a judge and will be tried in court (if not settled). Let's get into it.
Many people, ESPECIALLY Youtubers, have a false idea of exactly what Fair Use law is. Let's get into it: fair use is a legal defense, as Ethan and Hila stated in their video. What that means is NOT Ethan can say "this is fair use!" and Bold Guy + lawyer will say "aw shucks, you're right, nevermind." What it DOES mean is that Ethan and Hila can use this defense in court. Normally, the fair use defense, as often seen on Youtube, is used as a way of saying "well, even if you do take it to court, you won't win because I will have a good Fair Use defense". However, what is important to note here is that a judge has taken this case. What that means is that the judge doesn't necessarily agree with Hila & Ethan's "I will beat you in court because of Fair Use" idea. The judge wants to hear the case from both sides.
So let's take a closer look at Fair Use. Fair Use is comprised of four famous factors:
The purpose/character of the use (of the person who MAYBE infringed)
The nature of the original work
The amount of the original work taken (note: this is the weakest factor)
The market effect of the potential infringer on the original work.
The classic Youtube defense is the idea that videos are transformative (fits into factor #1), are critiques/reviews/commentaries (fits into factor #1), and the amount of the work taken is not more than necessary to accomplish those critiques/reviews/commentaries goals (fits into factor #3)
Let's breakdown what Ethan & Hila will argue in their Fair Use defense.
The work was transformative and was a commentary on the original work. Their selections of certain things to include, what not to include, and where to chop the video is considered 'transformative'.
Doesn't really apply, isn't necessary here.
They took no more than the necessary amount to accomplish their goal of commenting on the original work.
Market effect is low, given that there is no way an individual would click on Ethan & Hila's work expecting to see the full Bold Guy video - aka Ethan and Hila's work was not a "replacement" for the original work.
These are actually pretty good defenses. I have no idea if they will or will not fly in court - that's entirely up to a judge & jury (depending on questions of law or fact).
Now, a look at Bold Guy's rebuttal to their defense:
Ethan & Hila's work was not transformative at all. They took the entire video, chopped it up, and just inserted talking points between. The entire video is in there, and there was no conscious selection of what to include or what not to include, meaning it wasn't transformative. The video is also commercial - a noncommercial point from Ethan & Hila won't fly because they either directly or indirectly benefit, whether that be from advertising revenues or increased subscription counts respectively.
Not important.
They took the entire video (again, please note this is the least important factor of the four)
Ethan & Hila majorly disrupted Bold Guy's market. Most individuals that hoped to see the new Bold Guy video would go straight to his channel. Rather, people could see the thumbnail of Bold Guy's video, go straight to Ethan and Hila's video, and see all the content of the original video without even benefiting the original author.
What I bolded is what I consider to be the strongest factor of Bold Guy's case. However, again, this is an excellent and interesting copyright case - the reason why it was taken by a court is because there is no clear winner here.
I hope this helps some people understand some of the complexities of the issue. Simply "transformative" or "commentary" is not enough for Ethan & Hila to get away with no harm - this case is complex, and any Fair Use case involves countless moving parts.