I've been editing for a few years now, so I already have an editing reel which, as far as I know, should be clips without audio, set to music. But I also have a good deal of directing credits, and I want to get some of those into a reel. Do the same "rules" apply regarding sound?
I've personally never heard of the NO SOUND on an editing reel. So, I might be the wrong person to respond.
But, I would think that a director's reel (as well as an editors reel) should show off your talent.
Personally, if I was looking for someone to direct my feature, I'd need to see that they can get the best performance out of an actor.
The same would apply to editing.
If you're talking about music videos and such. I think a lot would depend on the content. There's loads of great low end videos. Unfortunately the music usually sucks. Which isn't the director's fault.