Does excessive movement during prayer—forwards and backwards from a mushaf placed on a stand—invalidate the prayer?

Firstly: There is no harm in reciting from the Mushaf (Qur'an) during prayer. The Shafi'is and Hanbalis have permitted this, and some of the Salaf (early Muslims) did so.

Secondly: Minor movements for the benefit of the prayer or out of necessity are permissible and do not invalidate the prayer. The Prophet (peace be upon him) moved during his prayer to open the door for Aisha and carried Umamah bint Abi al-Aas and then put her down. The jurists are of the opinion that minor and non-continuous movements do not invalidate the prayer; rather, they may be disliked if done intentionally without need.