Is verbal consent good enough?
No. Agreements in writing help to protect you from people who will forget their deal with you or change their mind later. If you want to use any film or video clips in your film where the film clip was made by another person, you need to make sure that person not only gives you the right to use the clip but that they are able to give you clear use of everything inside the film clip (ie people, locations, music, etc.) This is not a complete list of clearances but covers the major issues.
