Clipchamp
The editing website that I've decide to use is called Clipchamp. I mainly chose this website due to my classmates talking about using it, so I've decided why not check it out as well. To use the program you have to make an account first and that's what I did, but I just signed in with my side Gmail to use it. You can collaborate with others, lay music on top of each other, its accessible from anywhere, I'm not sure if you can mute or strip audio from the video because I haven't tried it yet.
Openshot
Openshot requires you to download the program, so it isn't web-based. The site that has the information about the program claims to be able to lay multiple tracks including audio tracks and backgrounds. The site doesn't say anything about being able to collaborate with others. The site also doesn't say anything about muting nor stripping the audio from videos, I'm going to assume that you can mute audio you add in yourself in the actual program.
Wevideo
It is web-based and you and download it if you want to, to use it web-based you just need to make an account just like Clipchamp. Its also accessible anywhere, you can even use it on your tablet, phone, and computer. You can lay tracks on top of each other, it starts off by giving you 3 tracks, but you can add more if you want to. You can't collaborate with others. Judging by how the program is set up I don't think you mute sounds from videos you add in, but you can strip and mute audio that you adding in yourself in the editing program as well.
