I suppose the argument could be made that someone could use longer clips and fill 10 seconds relatively easily

This is my whole reasoning. I know vidding is more work than fic (probably why I don't do it more :P), but I also don't want people seeing 10 seconds and slapping together something without any thought or effort. That said, I'll lower it to 20 seconds. :)

For the record, I don't undervalue vidding. I love watching them when done well and I know it takes a lot of effort to do them really well. I just don't people slapping something together because they think it's easy and not because they want to do it.