I'm also on Windows 7 but I am using Firefox. I don't think being on W7 by itself is a problem. I don't know what the problem could be on Chrome. I don't know anything about Chrome. You should also have figured out by now that I am not an employee of VDH. I'm just another user, like you.
There was one thing we had to do with VDH for Firefox after the first 8.0.0.x version appeared. I describe it in detail elsewhere on this forum. Look for a thread with the title "How to download from YouTube" & skip down to the post dated July 17. There are instructions there for an extra one-time step that we needed to perform. I don't know if it's relevant on Chrome. You can try it. Maybe it makes a difference, maybe not. Maybe it's not even available in Chrome. Like I say, I'm just another user but I don't have Chrome, never have, know nothing about it.
You should also try reloading whatever page you are trying to download from. You should also try launching playback for a couple of seconds. If the player on the web page offers a way to change resolution, try that, too. Try each thing at least 3 times. These are all tricks I have found useful with Firefox. Maybe they will help you, too.