So I have a few things to comment.
1. The tileset cut-off is really apparent in the video, due to the lighting used.
2. The level doesn't look that much fun. It has no decoration and barely any enemies.
3. You should add a way to get to the top of the flagpole.
4. There are some glitchy mechanics, like the podoboo getting stuck.
Overall, I actually adore this level, and do think its a really nice mechanic, but just a few minor bugs here and there. Is this your first time hacking NSMBU? If so, I think its an excelent start. Maybe by the next NSMBU level, you can have the things above in mind.