Yeah. Dumbbell section was added a few months ago. I have about 150 videos left to edit, upload and write instructions for. All of the dumbbell exercises being about 50 of those videos.
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.