Is it valid to complete a marriage via the Internet, with audio and video, between the bride's guardian and the groom, with the presence of witnesses from the bride's relatives, and the fulfillment of all the legitimate pillars and conditions of marriage?

If modern means of communication ensure against manipulation, and the identity of the husband and guardian is verified, and the two witnesses hear the offer and acceptance, then there is no harm in conducting the marriage through them. This is what Sheikh Ibn Baz and the Permanent Committee have ruled. However, it is more prudent to conduct the contract through an authorized representative (wakil).