I have worked in various in-house video departments over my career. Each one does this differently. One of the most successful models I have seen is basing your pricing on a project by project basis. They charge a flat fee for each video that is to be produced. In the contract, this includes, how many people will be interviewed, the length of the video, editing and 1 round of revisions, how the video will be delivered, etc. If they would like any changes to your initial contract, then additional fees are added.
This helps in the event things start to go wrong, and it is much easier in dealing with client relations when you go over on hours and the client would like to argue with you about the final price. In addition, it helps keep everything standard and makes it easier for you to figure out how long you need to spend on a project and helps balance out your work and personal lives.
I know that you are just starting out and it is a bit drowning to try to figure out what you feel your pricing should be but I feel that by basing your pricing on project basis can help with the beginning stages. Like Josh stated above, figure out how much you would like to base your take home profit to be and then add a bit to cover any additional expenses, like taxes and such. That should be how much you charge per video. If you end up taking less time than needed, then extra profit in your pocket.
Hope this helps.