Lovely website! One thing I noticed is that https://musclewiki.com/Dumbbells/Male/Hamstrings/ returns nothing. Maybe add some dumbell romanian deadlifts? Great stuff tho :)
Humble suggestion: if you have "slots" where you know you have videos to upload, I wonder if you could say as much rather than show the 404 page. That way, you can simply click through to other "equipment levels" without breaking the sequence.