Not sure which you are referring to, but they’ve both been around as creators on YouTube forever. They are both still actively making content. I’m not sure what memes you’re seeing, but maybe you’re just coming across communities with people that grew up watching this stuff more now. AVGN started in 2004 and Nostalgia Critic in 2007 so there’s a long history out there.
The casting choices are really questionable here. Looks like the casting was done to bring in a generic movie going audience that watches movies based on the cast, but this was only going to succeed by appealing to the actual fan base. Jack Black and Kevin Hart don’t need to be in every movie. I’m surprised Chris Pratt isn’t in this honestly.