RewriteEngine On
RewriteEngine On
RewriteCond %{HTTP_REFERER} !^http://(www.)?chanpuru.org/ [NC]
RewriteCond %{HTTP_REFERER} !^http://griever.xepher.net/ [NC]
RewriteRule .(jpg|gif|png)$ http://griever.xepher.net/images/no_hotlink.gif [R,L]
Same as you had above, minus the "!no_hotlink..." line. Since you're just protecting the screencaps directory, put the .htaccess file IN the screencaps folder, then no need for exceptions for the no_hotlink image, since it's in another folder. If you put the one you had directly in public_html, it would, in fact, break your whole site, as it only allows images to work if they're referenced by a page in "screencaps" so all OTHER images on your site would break. I also shortened the two conditions, so you can link screencaps from ANY part of your site(s) rather than just from pages that are also inside screencaps.
The second problem, is that you wrote the file in Macintosh text format, which doesn't get read as a proper config file, since macs put weird characters at the end of each line. You can either get a text editor that can save stuff in dos or unix/linux format, OR you can run the command "mac2unix" on the file to convert it after it's uploaded. That is... "mac2unix /home/griever/public_html/images/screencaps/.htaccess" (or whatever file you're converting.)
Anyway, I've already done all that for this go round, and your screencaps directory should be protected.