What is the ruling on keeping photographic images and video clips from a wedding, and what should be done about friends' photos that are on their phones?

The preponderant view is that photographic imaging is permissible as long as it does not include anything prohibited. Photographing women is permissible if the images are kept away from the sight of non-mahram men, although avoiding it is more virtuous as a preventative measure (sadd al-dhari'ah). There is no harm in video recording. However, spending exorbitant amounts of money on this may reach the level of prohibited extravagance.