Problem Is this too much resonance?

I'm finishing off a solsylva v bearing machine. 24" x 24" cutting area. Gecko 540, 300 oz/in, 3.5 Amp steppers. When I jog in the z and Y from around 50-100 in/min, I get loud vibration. I can jog the x axis at over 1000 in/min and it sounds fine, and over 600 in/min on the y (end of video). Is this too much resonance? What can I do to combat it? Anyone else build this machine?

Video:


Fast forward to 1:30 if you just want to see it moving.

Thanks,
Rich