Is it permissible to run one's fingers through the beard while washing the face during wudu, or must it be done at the end of wudu, as Sheikh Othman Al-Khamis mentioned?

"Combing the beard (takhlil al-lihya) is done with the washing of the face according to the majority of scholars. However, Imam Ahmad has a statement that says, 'If he wishes, he may comb it with his face, and if he wishes, when he wipes his head.' The matter is broad, and you may adopt either of the two opinions."