You can use ffmpeg or handbrake. They would allow you to edit any video (remove sections). Though it can be slow if you have an older machine.

I’m creating a bullet heaven. It will have incremental, and tower defense elements. The big feature is that users will create their own bullet patterns from BulletML scripts. Those bullets will interact with the world and NPCs in different ways. For example you shoot fireballs over grass, it’s gonna set it on fire, and turn into a tile of dirt.