"Couldn't load plug in" error when playing videos in google chrome on windows 7.

This can happen with PCs that are running the Enhanced Mitigation Toolkit.

If you are running EMT, do this:

1.  Start/All Programs
2.  Choose the Enhanced Mitigation Toolkit folder and select the EMT app
3.  Windows 7 has a pop up User Account Control Window - say "Yes"
4.  The EMT then appears.  Click on the "Configure Apps" button
5.  You'll see Chrome.exe listed at least once under the "App Name" column.  Uncheck the "SEHOP" boxes to the right of those chrome.exe entries.
6.  Choose OK
7.  Close the EMT window
8.  Close Google Chrome
9.  Reopen Google Chrome and go to a site like YouTube and run a video.  It might just work for you.