We study some dynamical properties in the context of bitransformation groups, and show that if (H,X,T) is a bitransformation group such that (H,X) is almost periodic and (X/H,T) is pointwise almost periodic $T_2$ and $x{in}X$, then $E_x={q{in}E(H,X){mid}qx{in}{overline{xT}}$ is a compact $T_2$ topological group and $E_{qx}=E_x(q{in}E(H,X))$ when H is abelian, where E(H,X) is the enveloping semigroup of the transformation group (H,X).