OK, now I've seen it.
You are standing up very straight.
It's hard to apply your weight to the rig (through the harness of course) when you are standing up that tall.
Are you using the inboard footstrap positions, or the outboard?
At no time in the short video clip do I see your rig fully raked back and sheeted in.
So, the bouncing I see the board doing is almost surely lack of mast foot pressure.
It's almost like you are controlling the pitch (fore and aft trim) angle of your board from the back of the board, rather than using the mast foot pressure to keep the nose down and allow you to flatten the board out so it will plane more freely.
We'll wait and see what others have to say now that they've seen the video.
Hope this helps,