It's a capacitive screen. The device needs to be grounded. I don't see the problem; it seems pretty easy to understand to me that to use the phone's screen properly, you need to have it grounded. This is like when people were complaining that you can't use the iPhone's screen with a pencil eraser (who does that!?!) and started using sausages (in China).
Is your phone behaving the way it is on the video?
I'm not an expert but wouldn't this mean that the whole screen would be non responsive and not just the top part? And that all phones with touchscreen would exhibit similar behavior? Or even, that ALL evos would have this issue?
From what I've seen (on my own phone and from videos such as the one referenced) and read on this and other forums:
1. It's just the top part of the touchscreen as the video clearly shows.
2. It doesn't appear to be an issue with ALL evos as others have stated that they do not have the issue.
3. It isn't an issue across all touchscreen phones (seems to be with evo and dinc)
There are times when I have the phone on my desk while browsing and a notification pops up. With the touchscreen issue, I would have to pick the phone up to pull down the notification bar (I know there are other ways to access the notification bar without swiping it down but why should a user have to do that when the notification bar is there for a reason).
And more importantly, my concern would be on whether the issue would get worse over time.
I'm sure Sprint has sold a couple of hundred thousand of these phones and online forums tend to magnify an issue to the point where it seems more wide spread than it actually is, but for those who've gotten a phone that is exhibiting this behavior it's little consolation.