Nice of you(not to mention courageous) to share the videos with us.
This low end Radar device would understate the speeds.
One reason has already been mentioned, that the reading is taken at some distance after contact, by which time the air resistance has slowed it down.
The other reason is that these Radar guns can only measure the component of velocity directly TOWARDS or AWAY from them.
According to my calculation the angle you have understates speed by 1.5% to 2%, or about 2 mph.