Everything that I'm describing has to do with unpublished work that has not yet been delivered to a client or published on your own.
I copyright everything I shoot no matter what it is. This includes family snapshots, outtakes and every frame that I shoot for my stock archive.
In order for this to be an easy and painless process you need to get your ducks in a row.
-You need to submit a digital file format that anyone can read. I use jpegs, but you could use PDF but probably not .psd files and certainly not raw files.
-If you are filing frequently you should set up a deposit account. This allows your account to be debited for each bulk submission. It costs $30.00 per submission whether you're submitting 100 shots or 20,000 shots. The deposit account can be established over the phone and paid and recharged with a credit card. It's easy.
-In order for your submission to arrive in a timely manner you need to ship it to the Copyright office via DHL, FedEx or UPS. Don't use the US Mail! It's still being delayed due to the anthrax deal in 2001.
-Submit on readable media like CD or DVD. Make it PC and Mac readable.
-Label your submission.
-Save the appropriate copyright PDF form on your own machine. It's a fillable form and can be filled out in 30 seconds.
http://www.copyright.gov/forms/formvas.pdf That's the one that I use, short form VA
-Sign your submission!
-Register as unpublished before your client gets their hands on it. That is your protection! Registered work gives you statutory protections.
Once you get familiar with the above suggestions you can create a submisssion is about two minutes with the majority of the time spent waiting for the CD/DVD to burn.
I submit only when I have a job to deliver to a client. At that time I add all the rest of my unregistered personal work as well as stuff that I shoot for stock. I average about 25 submissions per year.
I create a CD of jpegs in folders that match my naming and filing conventions. Once the disk is in transit I wait until the next day and use the shipping webiste of DHL or Fedex and make a PDF of the web page that shows delivery time and signature confirmation. When the actual copyright restistration arrives 2 to 7 months later I make a PDF copy and drop it in to each folder.