vfx green screening a multicolored item?

I'm still new to this and I've tried Google searching, finding Youtube tutorial videos ,etc and cant find anything that addresses my situation directly. I'm trying to key out the background but the focal item is multicolored and moving. I've tried multiple background colors and no matter what color i make the background keying it out also keys part of the focal item, I've also tried masking out the focal item but since its moving that only works for a frame or two. Can anyone give me advice on how to remove a background from a multicolored moving item from a 30 +/- second video?

Thanks in advance.
 
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