Make previews mandatory

I just came a cross a thread in the video section which is now 5 months old with about 50 links and not a single preview.
For me such threads are completely useless. You maybe can figure out what's behind the links but you can't be sure.
I don't want to discourage any poster, but i think we have enough tutorials on how to make previews that's it's not rocket science anymore. And if all the tools don't work, at least a precise description should be posted.
I saw that previews are not mentioned in the rules of forumophilia, but i think this should be mandatory.
Even if a thread makes it exactly clear what's in it (like a Jenna-Haze-thread) the previews can easily give you information about the file format, size and duration.

Yep, you're right ! Making previews is pretty easy with MediaPlayer Classic ! And previews are a big help for the leechers