Stop that jello in your video by setting these in place to dampen vibrations between your frame and arms. These are made of high density rubber and will squeeze into those tight places to reduce vibrations.
M3 Rubber Anti Vibration Washers
Inner Diameter: 3mm/0.12″
Outer Diameter: 8mm/0.3″
Thickness 4.5mm/0.18″ *Can be compressed to 2-3mm
Package: 16 washers