Fragmentation is the norm for video files, when one considers they’re taking 4 GB chunks out of your drive each time you want to do something. And the more DVDs you make, the worse fragmentation gets (as you know).
I don’t recommend that you “store” up to 5 dvds on your drive. Just do one dvd at a time, then delete the files after you’re finished and burned that 1 dvd to a DISC, not the hard drive. Then defragment. Then do another dvd. Repeat. If you have 5 dvds on your hard drive, you have committed the drive to at least 20 of your 80GB to store them. If they have to be further processed before you make them into a burned DVD, you’re likely to use up 40GB of your 80GB.
I also use O&O to defrag. If I leave O&O’s Autosense defrag on, it can come on right in the middle of encoding or burning, which is, needless to say, annoying. So, I check fragmentation levels manually.
I also check fragmentation levels after every dvd has been burned and I have removed the original files. I don’t get concerned until the fragmentation level reaches about 35 percent, then I just run O&O in the Stealth mode.
I usually try to keep my partition’s fragmentation level to no more than 10 percent; keeping a constant 5 percent level is ok, but not really necessary, at least for me. Finally, once a month, I do a thorough check of fragmentation and will sometimes use O&O’s Space mode.
Bottom line: How you handle fragmentation is a matter of personal taste, but fragmentation, and lots of it, is part of the video legend. And if you store more than 1 dvd at a time on your drive, your chances for problems increase. Not only that, but hard drives are only meant to be a staging area until you can burn your DVD to disc.