I see what your saying, but this is what I do.
I record films starting from when I see the action start to the finish, either tower, or grabbing out after that rare win

I label them very specifically... f4u vs so and so in a 109.
I try to watch the films once a week. I use to pretty much only fly on Saturday, so Sunday was the film watch day.... after I posted my cartoon. Being laid off I hope my flying time picks up and I find it harder to watch films.
After watching the films a few times to many each, I can be sure which I want to save, and which I want to trash.
I then go into windows explorer and delete, and move films around. I have folders for "plane type fights" and "people" fights. It is a good idea to keep the number of films in the film folder low. Each time the the record button is pushed the game scans to folder for the lowest number. If you have lots of films you will start to see little pauses in the game when you hit the record button. The viewer has the ability to "browse" different folders so it isn't much of a problem locating what you are looking to review.
While having a delete button in the viewer might be convenient you may delete films too quick. Ask around how many times people have clicked the delete button after making a film and then kick themselves in the back side after realizing they really wanted to save that one.