Thanks! This i already know. Maybe I was unclear. What I am looking for is safe way (CRC) to copy a whole file tree with folders within folders.

When I make a documentary I usually make a folder named after the project. I then make a folder for each major location or country that I film in. And within that folder I make one folder for each day of shooting.
Now - when I have ended up with a complex file structure and 300-400 Gigs of filming. How do I back up this safely. Using Clip manager and CTRL+A would take forever and the risk of making a mistake would be huge.

Today I am trusting Windows file copying but according to the people promoting CRC ON in this thread I should not. Is there a good third party application that does safe (CRC) copying and verifying?

If you're using a Mac I use a wonderful and inexpensive application called Chronosync. It does have a 'byte for byte' verification process. It copies the files from the source and then goes back and verifies that the copy is identical. They just came out with a new version that seems to be even better than the last.

My current backup for original video files, which I would consider to be about as important as it gets:

1) Use Clip Browser to safely copy from SxS or SDHC cards to a Drobo, full BPAV folder structure of whatever was on the card. Use the "safety" vs speed setting and the CRC.
2) Use Chronosync to sync the Drobo to another Drobo, with 'verification' on. I have this set to perform the copy night in the middle of the night when I'm not using the system. Chronosync is a pretty well-thought out application, it seems a bit daunting but there are really just a couple of settings that you need to set. I also have it set to 'archive' anything that it may find that would require a deletion from either Drobo. It stores these in a 'Archived' items folder. Then I can look through that folder at my leisure and make sure I really wanted to deleted from one of the Drobos.
3) As time permits, use Toast to copy from Drobo to DVD-Rs

The one thing you must remember is that you are dealing with data, i.e. number chrunching. You are not copying film material or other delicate materials, just 0's and 1's. So in theory and in practice, any good file copying software that can verify the data, should and will do the job perfectly. I have never had any problems with transferring files using File manager, I don't see any future problems with it either. However, to be on the safe side use a backup application that will verify your data. I am about to test a new item that has been sent to me called clickfree, this backs up data from hard drive to hard drive via a USB dongle, the software is in the dongle. I will report back and let you know.

Clickfree -- Save your data. Backup today.